JP2006178411A - Image forming method and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming method for making an electrophotographic image having high image density and excellent reproduction by preventing occurrence of image irregularity based on fog easy to occur by a counter developing method and density lowering of an edge part, and to provide an image forming apparatus. <P>SOLUTION: The image forming method comprises forming an electrostatic latent image on an organic photoreceptor, forming a developing brush by a developer containing toner on a cylindrical developing sleeve and bringing the developing brush into contact with the organic photoreceptor and clearly imaging the electrostatic latent image to a toner image. When making Dp50 of a 50% piece particle diameter of toner particles, the developer contains the toner in which the content of the toner particles in which the particle diameter is 0.7×(Dp50) or less is 8-piece% or less and water content is 0.1-2.0 mass% (in an environment of 30°C and 80% RH). The image forming method clearly images the electrostatic latent image to the toner image while rotating the developing sleeve in a counter direction to a rotation direction of the organic photoreceptor. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming method and an image forming apparatus used for electrophotographic image formation, and more particularly to an image forming method and an image forming apparatus used for electrophotographic image formation used in the field of copying machines and printers. Is.

  Electrophotographic photoconductors move from inorganic photoconductors such as Se, arsenic, arsenic / Se alloys, CdS, ZnO, etc. to organic photoconductors with excellent advantages such as pollution and ease of manufacture, and various materials are used. Organic photoreceptors (hereinafter also simply referred to as photoreceptors) have been developed.

  In recent years, function-separated type photoreceptors in which charge generation and charge transport functions are assigned to different materials have become the mainstream. For example, a charge generation layer and a charge transport layer are formed on an electrically conductive support via an intermediate layer. Laminated type photoreceptors are widely used (Patent Document 1).

  Turning to the electrophotographic process, latent image forming methods are roughly classified into analog image formation using a halogen lamp as a light source and digital image formation using an LED or laser as a light source. Recently, as a hard copy printer for a personal computer, and in an ordinary copying machine, a digital latent image forming method has been rapidly becoming mainstream because of the ease of image processing and the development of a multifunction device.

In the digital image forming method, an opportunity to produce an original print image is increased, and a demand for high image quality is increasing. In order to improve the image quality of the electrophotographic image, a technique for forming a fine dot image by forming a fine latent image on an organic photoreceptor using an exposure light source having a small spot diameter has been developed. For example, a method of forming a high-definition latent image on an organic photoreceptor using a light source having a spot diameter of 4000 μm ² or less is known (Patent Document 2). An organic photoconductor that can form a high-density and uniform latent image even when high-density dot exposure is performed with such a small spot diameter, and a development system that can reproduce the latent image as a toner image. The configuration is not yet fully achieved.

  That is, as a developing method of the latent image on the organic photoreceptor, a developing method (hereinafter referred to as a parallel developing method) in which a developing sleeve provided on the organic photoreceptor is advanced in the developing region in parallel with the traveling direction of the organic photoreceptor. A developing method (hereinafter referred to as a counter developing method) that advances in the counter direction is known. However, both of them have not sufficiently solved the problem in forming a high-density dot image.

  In the parallel development system in which the developing sleeve provided on the organic photoreceptor is advanced in parallel with the traveling direction of the organic photoreceptor, the developability of the periphery of the high density image is deteriorated, the density is likely to be insufficient, and the contrast is high. The image quality is likely to deteriorate in a photographic image or the like.

  On the other hand, the developing method that proceeds in the counter direction has high developability and can form a high-density dot image, but often the image is fogged or the density is insufficient at the tip.

  It has been found that the above-described phenomena are not sufficiently solved by merely improving the developer, and these phenomena are emphasized or improved by the characteristics of the organic photoreceptor.

  That is, it is presumed to be related to the contrast of the electrostatic latent image formed on the organic photoreceptor and the production of reversely charged toner due to the friction between the organic photoreceptor and the developer.

  That is, even if the electrostatic latent image is formed with high definition, in the counter development method, if the toner charge amount distribution is broad, reversely chargeable toner is likely to be generated, resulting in toner scattering, The density at the tip is likely to decrease, and a high-definition electrostatic latent image cannot be reproduced as a toner image. Conventionally, it has been proposed to use polymerized toner having a narrow particle size distribution as a developing means (Patent Document 3). However, it has been found that with the toner of the particle size distribution proposed here, the occurrence of toner scattering cannot be sufficiently suppressed by the counter development method, and a high-definition electrostatic latent image cannot be reproduced as a toner image.

Recently, a fine unevenness failure called worm-like unevenness has been a problem. Although the cause of this worm-like unevenness has not been clarified, it is considered that the worm-like unevenness is caused by the fact that the relative speed between the photosensitive member and the developing sleeve is high and the frictional charging between the magnetic brush of the developer and the photosensitive member becomes strong. . For this reason, worm-like unevenness tends to occur more easily in the counter development method than in the parallel development method. Further, the worm-like unevenness has a correlation with the frequency of the developing bias, and the worm-like unevenness is reduced as the frequency is increased. However, when the frequency is increased, the sharpness of the image tends to decrease, and it is difficult to satisfy both the reduction of worm-like unevenness and the sharpness of the image.
JP 2004-133018 A JP-A-8-272197 JP 2002-244336 A

  The present invention relates to an image forming method that solves the problems of the prior art as described above, that is, solves the problems that easily occur in the counter development method, and stably forms a high-definition digital image. More specifically, it is possible to produce an electrophotographic image with high image density and good color reproducibility by preventing occurrence of fog and worm-like unevenness due to fogging and a decrease in tip density, which are likely to occur in the counter development method. An image forming method and an image forming apparatus are provided.

  In order to eliminate the above-mentioned problems of the present invention, that is, the occurrence of fog and partial density deficiency that are likely to occur in the counter development method, and to obtain a uniform and high-definition electrophotographic image, the constitution of the developer, organic As a result of examining the relationship between the structure of the photoconductor and the developing method, the toner used in the developer is used to prevent fogging in the counter method having excellent developability, density defects at the leading edge of the image, and worm-like unevenness. The inventors have found that it is effective to reduce the amount of the minute toner component and to reduce the water content of the toner, and the present invention has been completed.

  In other words, by making the counter development method appropriate, the problem of fogging and the density defect at the front end of the image could be improved to some extent, but both the prevention of fine unevenness called worm-like unevenness and the improvement of sharpness are achieved. I couldn't do it. Accordingly, as a result of intensive studies by the present inventors, in the counter development method, the above-described compatibility is achieved by using the toner of the present invention, and further, the problem of fog generation and density defect at the front end of the image is improved. I found that I can do it. The reason why it was possible to prevent both fine unevenness failure called worm-like unevenness and improved sharpness is not clear, but the narrowness of toner distribution and the appropriate water content of the present invention are It is presumed that there is the same effect as if the development bias frequency was increased by reducing the variation in the characteristics.

That is, the present invention is achieved by having the following configuration.
1. An electrostatic latent image is formed on the organic photoconductor, a developing brush made of a developer containing toner is formed on a cylindrical developing sleeve, the developing brush is brought into contact with the organic photoconductor, and the electrostatic latent image is formed. In the image forming method for visualizing a toner image, the developer has a toner particle content of 0.7 × (Dp50) or less of 8 particles, where the 50% number particle size of the toner particles is Dp50. % And a toner having a water content of 0.1 to 2.0% by mass (under an environment of 30 ° C. and 80% RH), the developing sleeve is in the counter direction with respect to the rotation direction of the organic photoreceptor. An image forming method characterized in that an electrostatic latent image is visualized as a toner image while being rotated.
2. An electrostatic latent image is formed on the organic photoconductor, a developing brush made of a developer containing toner is formed on a cylindrical developing sleeve, the developing brush is brought into contact with the organic photoconductor, and the electrostatic latent image is formed. A plurality of image forming units each having a developing unit that visualizes a toner image and a transfer unit that transfers a toner image formed on an organic photoconductor to a transfer medium are provided, and the coloration is changed for each of the plurality of image forming units. In the image forming method of forming a color image by forming each color toner image on an organic photoreceptor using the prepared toner, and transferring the color toner image from the organic photoreceptor to a transfer medium, the developer contains toner particles. When the 50% number particle size is Dp50, the content of toner particles having a particle size of 0.7 × (Dp50) or less is 8 number% or less and the water content is 0.1 to 2.0% by mass (30 ° C. In an 80% RH environment) That contains toner with respect to the rotation direction of the organic photoreceptor, an image forming method characterized in that the electrostatic latent image into a toner image while rotating the developing sleeve in the counter direction.
3. The toner has a ratio (Dv50 / Dp50) of 50% volume particle size (Dv50) to 50% number particle size (Dp50) of toner particles of 1.0 to 1.11. A toner having a ratio (Dv75 / Dp75) of 75% volume particle size (Dv75) to cumulative 75% number particle size (Dp75) from the larger number particle size of 1.0 to 1.10. 3. The image forming method as described in 1 or 2 above.
4). 4. The image forming method according to any one of 1 to 3, wherein the toner particles have a 50% volume particle diameter (Dv50) of 2 to 9 μm.
5. The organic photoconductor has a photosensitive layer through an intermediate layer containing N-type semiconductive particles having a number average primary particle size of 3 to 200 nm in a binder resin on a conductive support. 5. The image forming method according to any one of 4 above.
6). 6. The image forming method as described in 5 above, wherein the N-type semiconductor particles are titanium oxide or zinc oxide.
7). 7. The image forming method as described in 6 above, wherein the N-type semiconductor particles are titanium oxide.
8). 8. The image forming method as described in 7 above, wherein the titanium oxide is a rutile titanium oxide pigment or an anatase titanium oxide pigment.
9. 9. The image forming method according to any one of 1 to 8, wherein a developing gap (Dsd) between the organic photoreceptor and the developing sleeve is 0.2 to 0.6 mm.
10. 10. The image formation as described in any one of 1 to 9 above, wherein a penetration depth (Bsd) of the magnetic brush in a developing region between the organic photoreceptor and the developing sleeve is 0.0 to 0.8 mm. Method.
11. 11. The image forming method as described in 1 to 10 above, wherein a peripheral speed ratio (Vs / Vopc) between the developing sleeve and the organic photoreceptor is 1.2 to 3.0.
12 The difference | V0−Vdc | between the surface potential V0 of the organic photoreceptor and the DC component Vdc of the developing bias applied to the developing sleeve is 100 to 300V, the DC component Vdc of the developing bias is −300V to −650V, The image forming method according to any one of 9 to 11, wherein the AC component Vac is 0.5 to 1.5 kV, the frequency is 3 to 9 kHz, the duty is 45 to 70%, and a rectangular wave.
13. An electrostatic latent image is formed on the organic photoconductor, a developing brush made of a developer containing toner is formed on a cylindrical developing sleeve, the developing brush is brought into contact with the organic photoconductor, and the electrostatic latent image is formed. In the image forming apparatus that visualizes a toner image, the developer has a toner particle content of 0.7 × (Dp50) or less of 8 particles, where the 50% number particle size of the toner particles is Dp50. % And a toner having a water content of 0.1 to 2.0% by mass (under an environment of 30 ° C. and 80% RH), the developing sleeve is in the counter direction with respect to the rotation direction of the organic photoreceptor. An image forming apparatus characterized in that an electrostatic latent image is visualized as a toner image while being rotated.
14 An electrostatic latent image is formed on the organic photoconductor, a developing brush made of a developer containing toner is formed on a cylindrical developing sleeve, the developing brush is brought into contact with the organic photoconductor, and the electrostatic latent image is formed. A plurality of image forming units each having a developing unit that visualizes a toner image and a transfer unit that transfers a toner image formed on an organic photoconductor to a transfer medium are provided, and the coloration is changed for each of the plurality of image forming units. In the image forming apparatus for forming a color image by forming each color toner image on the organic photoreceptor using the prepared toner, and transferring the color toner image from the organic photoreceptor to a transfer medium, the developer contains toner particles. When the 50% number particle size is Dp50, the content of toner particles having a particle size of 0.7 × (Dp50) or less is 8 number% or less and the water content is 0.1 to 2.0% by mass (30 ° C. In an 80% RH environment) That contains toner with respect to the rotation direction of the organic photoreceptor, an image forming apparatus characterized by the electrostatic latent image into a toner image while rotating the developing sleeve in the counter direction.

  By using the image forming method and the image forming apparatus of the present invention, it is possible to prevent the occurrence of fog and density defects at the tip portion that are likely to occur in the counter development method, and further eliminate fine unevenness called worm-like unevenness, An electrophotographic image with good color reproducibility can be provided.

  Hereinafter, the present invention will be described in detail.

  In the image forming method of the present invention, an electrostatic latent image is formed on an organic photoreceptor, a developing brush is formed with a developer containing toner on a cylindrical developing sleeve, and the developing brush is brought into contact with the organic photoreceptor. Thus, in the image forming method of visualizing the electrostatic latent image into a toner image, the developer has a particle size of 0.7 × (Dp50) or less, where Dp50 is the 50% number particle size of the toner particles. A toner having a toner particle content of 8% by number or less and a water content of 0.1 to 2.0% by mass (30 ° C., 80% RH environment) is contained in the rotational direction of the organic photoreceptor. On the other hand, the electrostatic latent image is visualized as a toner image while rotating the developing sleeve in the counter direction.

  In the image forming method of the present invention, an electrostatic latent image is formed on an organic photoreceptor, a developing brush is formed with a developer containing toner on a cylindrical developing sleeve, and the developing brush is applied to the organic photoreceptor. A plurality of image forming units having a developing unit that visualizes the electrostatic latent image into a toner image in contact with each other and a transfer unit that transfers the toner image formed on the organic photosensitive member to a transfer medium are arranged and provided. Image forming method for forming a color toner image on an organic photoreceptor using toner whose color is changed for each of a plurality of image forming units, and transferring the color toner images from the organic photoreceptor to a transfer medium to form a color image In the developer, the toner particle content of 0.7 × (Dp50) or less is 8% by number or less and the water content is 0. 1 to 2.0% by mass ( 0.degree. C. and 80% RH environment), and developing the electrostatic latent image into a toner image while rotating the developing sleeve in the counter direction with respect to the rotation direction of the organic photoreceptor. And

  Since the image forming method of the present invention has the above-described configuration, it is possible to prevent the occurrence of fogging and the density defect at the tip portion, which are easily generated by the counter development method, and provide a high-quality digital image or color image.

  On the other hand, the developer according to the present invention contains a toner having a particle size of 0.7 × (Dp50) or less and having a toner particle content of 8 number% or less, where Dp50 is the 50% number particle size of the toner particles. To do.

  When the content of toner particles having a particle size of 0.7 × (Dp50) or less exceeds 8% by number, the abundance ratio of small particle size components increases, resulting in an increase in weakly charged toner, generation of reverse polarity toner, or overcharging. This may cause toner generation. As a result, fog and tip density reduction are likely to occur in the counter development method, and color reproducibility is likely to deteriorate in color images.

  The water content of the toner is strongly related to the chargeability and charge retention of the toner. In the present invention, the toner having the above distribution characteristics has a water content in the range of 0.1 to 2.0% by weight. It was found that the charge rise and charge retention of the film were good. When the water content is less than 0.1% by mass, the charge rising characteristics are deteriorated and a weakly charged toner is likely to be generated. In the counter developing method, fog and a decrease in the density of the tip end portion are likely to occur. On the other hand, when the water content exceeds 2.0% by mass, the charge retention of the toner is lowered, the image density is liable to be lowered, and the tip end density is liable to be lowered.

  Further, in the particle size distribution of the toner according to the present invention, the ratio (Dv50 / Dp50) of 50% volume particle size (Dv50) to 50% number particle size (Dp50) is preferably 1.0 to 1.11, more preferably. 1.0-1.10.

  The ratio (Dv75 / Dp75) of the cumulative 75% volume particle size (Dv75) from the larger toner particle to the cumulative 75% number particle size (Dp75) is preferably 1.0 to 1.10. When the ratio exceeds 1.10, the abundance ratio of small particle size components increases, which causes an increase in weakly charged components, generation of reverse polarity toner, or generation of overcharged components. As a result, fog and tip density reduction are likely to occur in the counter development method, and color reproducibility is likely to deteriorate in color images.

  The volume average particle diameter of the toner, that is, the 50% volume particle diameter (Dv50) is preferably 2 to 9 μm, more preferably 3 to 7 μm. By setting this range, the resolution can be increased. In addition, by combining with the above range, the amount of toner having a fine particle diameter can be reduced while being a small particle diameter toner, the dot image reproducibility is improved over a long period of time, and the sharpness is excellent. In addition, a stable image can be formed.

  In the present invention, the cumulative 75% volume particle diameter (Dv75) or cumulative 75% number particle diameter (Dp75) from the larger one is the cumulative frequency from the larger particle diameter, the sum of the total volume or the sum of the numbers. On the other hand, each is represented by a volume particle size or a number particle size of a particle size distribution portion showing 75%.

  In the present invention, the particle size distribution, 50% volume particle size (Dv50), 50% number particle size (Dp50), cumulative 75% volume particle size (Dv75), cumulative 75% number particle size (Dp75), etc. It can be measured using a resistance type particle size distribution analyzer SD-2000.

  In the technical field where an electrostatic latent image is visualized by dry development, a toner obtained by adding an external additive or the like to at least colored particles (prototype of toner particles) composed of a colorant and a resin is used as a toner. . However, as long as there is no particular problem, the colored particles and the toner are generally described without distinction. In the particle size and particle size distribution in the present invention, there is no change in the measured value when either colored particles or toner particles are measured.

  Further, the diameter of external additives and the like is on the order of nm (number average primary particles), and can be measured with a light scattering electrophoresis particle size measuring device “ELS-800” (manufactured by Otsuka Electronics Co., Ltd.).

  Hereinafter, the configuration and production method of the toner used in the present invention showing the above-described particle size distribution will be described in detail.

<toner>
The toner used in the present invention may be a pulverized toner or a polymerized toner as long as it is a toner prepared in the above range, but the toner according to the present invention is prepared by a polymerization method from the viewpoint of obtaining a stable particle size distribution. Polymerizable toners that can be used are preferred.

  The term “polymerized toner” refers to a toner whose binder resin (resin particles) for toner is formed and whose toner shape is formed by polymerization of the raw material monomer of the binder resin and, if necessary, subsequent chemical treatment. More specifically, it means a toner formed through a polymerization reaction such as suspension polymerization or emulsion polymerization, and if necessary, a step of fusing particles between them.

  In the present invention, it is preferable to use associative toner obtained by salting out / fusing resin particles containing a release agent and a colorant as toner.

  This is because, in addition to being able to produce a toner having the particle size distribution as described above, the associative toner has a uniform surface property between the toner particles, and the effects of the present invention can be achieved without impairing the transferability. It is estimated that he was able to demonstrate.

  The above-mentioned “salting out / fusion” means that salting out (aggregation of particles) and fusion (disappearance of the interface between particles) occur at the same time, or act of causing salting out and fusion at the same time. . In order to perform salting-out and fusion at the same time, it is necessary to agglomerate particles (resin particles, colorant) under a temperature condition equal to or higher than the glass transition temperature (Tg) of the resin constituting the resin particles.

<Release agent>
The release agent constituting the toner according to the present invention is not particularly limited, but is a crystalline ester compound represented by the following general formula (5) (hereinafter referred to as “specific ester compound”). It is preferable that

Formula _{(5): R 1 - (} OCO-R 2) n
(In the formula, each of R ₁ and R ₂ represents a hydrocarbon group having 1 to 40 carbon atoms which may have a substituent, and n is an integer of 1 to 4).
<Specific ester compounds>
In general formula (5) which shows a specific ester compound, R < ₁ > and R < ₂ > show the hydrocarbon group which may have a substituent, respectively.

The hydrocarbon group R ₁ has 1 to 40 carbon atoms, preferably 1 to 20 carbon atoms, more preferably 2 to 5 carbon atoms.

The hydrocarbon group R ₂ has 1 to 40 carbon atoms, preferably 16 to 30 carbon atoms, more preferably 18 to 26 carbon atoms.

  In the general formula (5), n is an integer of 1 to 4, preferably 2 to 4, more preferably 3 to 4, and particularly preferably 4.

  The specific ester compound can be suitably synthesized by a dehydration condensation reaction between an alcohol and a carboxylic acid.

  The most preferred specific ester compound may include pentaerythritol tetrabehenate.

  Specific examples of the specific ester compound include compounds represented by the following formulas 1) to 26).

<Ratio of release agent>
The content ratio of the release agent in the toner according to the present invention is usually 1 to 30% by mass, preferably 2 to 20% by mass, and more preferably 3 to 15% by mass.

<Resin particles containing release agent>
In the present invention, “resin particles containing a release agent” means that a release agent is dissolved in a monomer for obtaining resin particles, and the resulting monomer solution is dispersed in an aqueous medium. By polymerizing, it can be obtained as latex particles.

  The resin particles preferably have a weight average particle diameter of 50 to 2000 nm.

  Examples of the polymerization method for obtaining resin particles containing a release agent include granulation polymerization methods such as an emulsion polymerization method, a suspension polymerization method, and a seed polymerization method.

  As a preferable polymerization method for obtaining resin particles containing a release agent, a release agent is dissolved in a monomer in an aqueous medium in which a surfactant having a concentration equal to or lower than the critical micelle concentration is dissolved. A monomer solution is dispersed in oil droplets using mechanical energy to prepare a dispersion, and a water-soluble polymerization initiator is added to the resulting dispersion to perform radical polymerization (hereinafter referred to as this specification). (Referred to as “mini-emulsion method”). Instead of adding a water-soluble polymerization initiator, or while adding the water-soluble polymerization initiator, an oil-soluble polymerization initiator may be added to the monomer solution.

  Here, a dispersing machine for dispersing oil droplets by mechanical energy is not particularly limited. For example, a stirring device “CLEARMIX” (M-Technique) equipped with a rotor that rotates at high speed is used. (Manufactured by Co., Ltd.), ultrasonic disperser, mechanical homogenizer, manton gorin, pressure homogenizer, and the like. The dispersed particle diameter is 10 to 1000 nm, preferably 30 to 300 nm.

<Binder resin>
The binder resin constituting the toner according to the present invention comprises a high molecular weight component having a peak or shoulder in the region of 100,000 to 1,000,000 in the molecular weight distribution measured by GPC, and 1,000 to 20,000. A resin containing a low molecular weight component having a peak or shoulder in the region is preferable.

  Here, as a method for measuring the molecular weight of the resin by GPC, 1 ml of THF is added to 0.5 to 5.0 mg (specifically 1 mg) of a measurement sample, and stirring is performed at room temperature using a magnetic stirrer or the like. Go and dissolve well. Subsequently, after processing with a membrane filter having a pore size of 0.45 to 0.50 μm, the solution is injected into GPC.

  As GPC measurement conditions, the column is stabilized at 40 ° C., THF is allowed to flow at a flow rate of 1 ml per minute, and about 100 μl of a sample having a concentration of 1 mg / ml is injected for measurement. The column is preferably used in combination with a commercially available polystyrene gel column. For example, combinations of Shodex GPC KF-801, 802, 803, 804, 805, 806, and 807 manufactured by Showa Denko KK and TSKgel G1000H, G2000H, G3000H, G4000H, G6000H, G7000H, TSK guard column manufactured by Tosoh Corporation Combinations can be mentioned. As a detector, a refractive index detector (IR detector) or a UV detector may be used. In the measurement of the molecular weight of a sample, the molecular weight distribution of the sample is calculated using a calibration curve prepared using monodisperse polystyrene standard particles. About 10 points may be used as polystyrene for preparing a calibration curve.

  Hereinafter, the constituent material of resin particles and the preparation method (polymerization method) will be described.

(Monomer)
As the polymerizable monomer used for obtaining the resin particles (binder resin), a radical polymerizable monomer is an essential component, and a crosslinking agent can be used as necessary. Moreover, it is preferable to contain at least one radical polymerizable monomer having the following acidic group or radical polymerizable monomer having a basic group.

(1) Radical polymerizable monomer:
The radical polymerizable monomer is not particularly limited, and a conventionally known radical polymerizable monomer can be used. Moreover, it can be used combining 1 type (s) or 2 or more types so that the required characteristic may be satisfy | filled.

  Specifically, aromatic vinyl monomers, (meth) acrylic acid ester monomers, vinyl ester monomers, vinyl ether monomers, monoolefin monomers, diolefin monomers , Halogenated olefin monomers and the like can be used.

  Examples of the aromatic vinyl monomer include styrene, o-methyl styrene, m-methyl styrene, p-methyl styrene, p-methoxy styrene, p-phenyl styrene, p-chloro styrene, p-ethyl styrene, p. -N-butyl styrene, p-tert-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, 2, Examples thereof include styrene monomers such as 4-dimethylstyrene and 3,4-dichlorostyrene and derivatives thereof.

  Examples of (meth) acrylic acid ester monomers include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, and methacrylic acid. Examples include butyl, hexyl methacrylate, 2-ethylhexyl methacrylate, ethyl β-hydroxyacrylate, propyl γ-aminoacrylate, stearyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, and the like.

  Examples of vinyl ester monomers include vinyl acetate, vinyl propionate, and vinyl benzoate.

  Examples of the vinyl ether monomer include vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether, vinyl phenyl ether and the like.

  Examples of the monoolefin monomer include ethylene, propylene, isobutylene, 1-butene, 1-pentene, 4-methyl-1-pentene and the like.

  Examples of the diolefin monomer include butadiene, isoprene, chloroprene and the like.

  Examples of the halogenated olefin monomer include vinyl chloride, vinylidene chloride, vinyl bromide and the like.

(2) Crosslinking agent:
As the crosslinking agent, a radical polymerizable crosslinking agent may be added in order to improve the properties of the toner. Examples of the radical polymerizable crosslinking agent include those having two or more unsaturated bonds such as divinylbenzene, divinylnaphthalene, divinyl ether, diethylene glycol methacrylate, ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, and diallyl phthalate.

(3) Radical polymerizable monomer having an acidic group or a basic group:
Examples of the radical polymerizable monomer having an acidic group or the radical polymerizable monomer having a basic group include a carboxyl group-containing monomer, a sulfonic acid group-containing monomer, a primary amine, and a secondary group. Amine-based compounds such as amines, tertiary amines, and quaternary ammonium salts can be used.

  Examples of the radical polymerizable monomer having an acidic group include carboxylic acid group-containing monomers such as acrylic acid, methacrylic acid, fumaric acid, maleic acid, itaconic acid, cinnamic acid, maleic acid monobutyl ester, and maleic acid monoester. An octyl ester etc. are mentioned.

  Examples of the sulfonic acid group-containing monomer include styrene sulfonic acid, allyl sulfosuccinic acid, octyl allyl sulfosuccinate and the like.

  These may have a structure of an alkali metal salt such as sodium or potassium or an alkaline earth metal salt such as calcium.

  Examples of the radical polymerizable monomer having a basic group include amine compounds, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, and quaternary ammonium salts of the above four compounds, 3-dimethylaminophenyl acrylate, 2-hydroxy-3-methacryloxypropyltrimethylammonium salt, acrylamide, N-butylacrylamide, N, N-dibutylacrylamide, piperidylacrylamide, methacrylamide, N-butylmethacrylamide, N-octadecylacrylamide Vinyl pyridine, vinyl pyrrolidone; vinyl N-methylpyridinium chloride, vinyl N-ethylpyridinium chloride, N, N-diary Ammonium chloride, N, N-diallyl-ethyl ammonium chloride, and the like.

  As the radical polymerizable monomer used in the present invention, a radical polymerizable monomer having an acidic group or a radical polymerizable monomer having a basic group is used in an amount of 0.1 to 15% by mass based on the whole monomer. The radical polymerizable crosslinking agent is preferably used in the range of 0.1 to 10% by mass with respect to the total radical polymerizable monomer, although it depends on its properties.

[Chain transfer agent]
For the purpose of adjusting the molecular weight of the resin particles, it is possible to use a commonly used chain transfer agent.

  The chain transfer agent is not particularly limited, for example, mercaptans such as octyl mercaptan, dodecyl mercaptan, tert-dodecyl mercaptan, mercaptopropionates such as n-octyl-3-mercaptopropionate, carbon tetrabromide, etc. And styrene dimer etc. are used.

(Polymerization initiator)
The radical polymerization initiator used in the present invention can be appropriately used as long as it is water-soluble. For example, persulfates (potassium persulfate, ammonium persulfate, etc.), azo compounds (4,4′-azobis-4-cyanovaleric acid and its salts, 2,2′-azobis (2-amidinopropane) salts, etc.), peroxides Compounds and the like.

  Furthermore, the radical polymerization initiator can be combined with a reducing agent as necessary to form a redox initiator. By using a redox initiator, the polymerization activity is increased, the polymerization temperature is lowered, and the polymerization time can be further shortened.

  The polymerization temperature may be any temperature as long as it is equal to or higher than the lowest radical generation temperature of the polymerization initiator, but for example, a range of 50 ° C. to 90 ° C. is used. However, it is possible to perform polymerization at room temperature or higher by using a polymerization initiator that starts at room temperature, for example, a combination of hydrogen peroxide and a reducing agent (ascorbic acid or the like).

[Surfactant]
In order to perform polymerization using the above-mentioned radical polymerizable monomer, it is necessary to perform oil droplet dispersion in an aqueous medium using a surfactant. Although it does not specifically limit as surfactant which can be used in this case, The following ionic surfactant can be mentioned as an example of a suitable thing.

  Examples of the ionic surfactant include sulfonates (sodium dodecylbenzenesulfonate, sodium arylalkylpolyethersulfonate, 3,3-disulfonediphenylurea-4,4-diazo-bis-amino-8-naphthol-6 Sodium sulfonate, ortho-carboxybenzene-azo-dimethylaniline, 2,2,5,5-tetramethyl-triphenylmethane-4,4-diazo-bis-β-naphthol-6-sodium sulfonate, etc.), sulfuric acid Ester salts (sodium dodecyl sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, etc.), fatty acid salts (sodium oleate, sodium laurate, sodium caprate, sodium caprylate, sodium caproate, potassium stearate) Beam, calcium oleate and the like).

  Nonionic surfactants can also be used. Specifically, polyethylene oxide, polypropylene oxide, combination of polypropylene oxide and polyethylene oxide, ester of polyethylene glycol and higher fatty acid, alkylphenol polyethylene oxide, ester of higher fatty acid and polyethylene glycol, ester of higher fatty acid and polypropylene oxide, sorbitan ester Etc.

<Colorant>
Examples of the colorant constituting the toner according to the present invention include inorganic pigments, organic pigments, and dyes.

  A conventionally well-known thing can be used as an inorganic pigment. Specific inorganic pigments are exemplified below.

  Examples of the black pigment include carbon black such as furnace black, channel black, acetylene black, thermal black, and lamp black, and magnetic powder such as magnetite and ferrite.

  These inorganic pigments can be used alone or in combination as required. Moreover, the addition amount of a pigment is 2-20 mass% with respect to a polymer, Preferably 3-15 mass% is selected.

  When used as a magnetic toner, the above-mentioned magnetite can be added. In this case, it is preferable to add 20 to 60% by mass in the toner from the viewpoint of imparting predetermined magnetic properties.

  Conventionally known organic pigments and dyes can also be used. Specific organic pigments and dyes are exemplified below.

  Examples of pigments for magenta or red include C.I. I. Pigment red 2, C.I. I. Pigment red 3, C.I. I. Pigment red 5, C.I. I. Pigment red 6, C.I. I. Pigment red 7, C.I. I. Pigment red 15, C.I. I. Pigment red 16, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 53: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 139, C.I. I. Pigment red 144, C.I. I. Pigment red 149, C.I. I. Pigment red 166, C.I. I. Pigment red 177, C.I. I. Pigment red 178, C.I. I. And CI Pigment Red 222.

  Examples of the orange or yellow pigment include C.I. I. Pigment orange 31, C.I. I. Pigment orange 43, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 15, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 94, C.I. I. Pigment yellow 138, C.I. I. Pigment yellow 180, C.I. I. Pigment yellow 185, C.I. I. Pigment yellow 155, C.I. I. And CI Pigment Yellow 156.

  Examples of pigments for green or cyan include C.I. I. Pigment blue 15, C.I. I. Pigment blue 15: 2, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 16, C.I. I. Pigment blue 60, C.I. I. And CI Pigment Green 7.

  As the dye, C.I. I. Solvent Red 1, 49, 52, 58, 63, 111, 122, C.I. I. Solvent Yellow 19, 44, 77, 79, 81, 82, 93, 98, 103, 104, 112, 162, C.I. I. Solvent Blue 25, 36, 60, 70, 93, 95 etc. can be used, and a mixture thereof can also be used.

  These organic pigments and dyes can be used alone or in combination as desired. Moreover, the addition amount of a pigment is 2-20 mass% with respect to a polymer, Preferably 3-15 mass% is selected.

  The colorant can also be used after surface modification. As the surface modifier, conventionally known ones can be used, and specifically, silane coupling agents, titanium coupling agents, aluminum coupling agents and the like can be preferably used.

<External additive>
The toner according to the present invention can be used by adding a so-called external additive for the purpose of improving fluidity, chargeability and cleaning property. These external additives are not particularly limited, and various inorganic fine particles, organic fine particles and lubricants can be used.

  A conventionally well-known thing can be used as an inorganic fine particle. Specifically, silica, titanium, alumina fine particles and the like can be preferably used. These inorganic fine particles are preferably hydrophobic. Specifically, as silica fine particles, for example, commercially available products R805, R976, R974, R972, R812, R809 manufactured by Nippon Aerosil Co., Ltd., HVK2150, H200 manufactured by Hoechst, and commercially available products TS720, TS530, TS610, H5 manufactured by Cabot Corporation. MS5 and the like.

  Examples of the titanium fine particles include commercially available products T-805 and T-604 manufactured by Nippon Aerosil Co., Ltd., commercially available products MT-100S, MT-100B, MT-500BS, MT-600, MT-600SS, and JA- 1. Commercial products TA-300SI, TA-500, TAF-130, TAF-510, TAF-510T manufactured by Fuji Titanium Co., Ltd. Commercial products IT-S, IT-OA, IT-OB, IT- manufactured by Idemitsu Kosan Co., Ltd. OC etc. are mentioned.

  Examples of the alumina fine particles include commercial products RFY-C and C-604 manufactured by Nippon Aerosil Co., Ltd. and commercial products TTO-55 manufactured by Ishihara Sangyo Co., Ltd.

  As the organic fine particles, spherical organic fine particles having a number average primary particle diameter of about 10 to 2000 nm can be used. As this, a homopolymer such as styrene or methyl methacrylate or a copolymer thereof can be used.

  Examples of lubricants include, for example, zinc stearate, aluminum, copper, magnesium, calcium, etc., zinc oleate, manganese, iron, copper, magnesium, etc., zinc palmitate, copper, magnesium, calcium, etc. And salts of higher fatty acids such as zinc of linoleic acid, salts of calcium, etc., zinc of ricinoleic acid, salts of calcium, etc.

  The amount of these external additives added is preferably 0.1 to 5% by mass with respect to the toner.

  The toner according to the present invention is preferably an associative toner obtained by salting out / fusing a resin particle containing a release agent and a colorant in an aqueous medium. As described above, by salting out / fusing the resin particles containing the release agent, a toner in which the release agent is finely dispersed can be obtained, and in addition to the effect of the particle size distribution, the chargeability can be obtained. It is possible to exhibit effects such as stabilization.

  The toner according to the present invention has an irregular shape on the surface from the time of manufacture, and is an associative toner obtained by fusing resin particles and a colorant in an aqueous medium. Therefore, the difference in shape and surface property between toner particles is extremely small, and as a result, the surface property tends to be uniform. For this reason, a difference in transferability and chargeability between toners hardly occurs, and an image can be kept good.

<Toner manufacturing process>
As an example of a method for producing the toner according to the present invention,
(1) a dissolution step of preparing a monomer solution by dissolving a release agent in the monomer;
(2) A dispersion step of dispersing the obtained monomer solution in an aqueous medium,
(3) a polymerization step of preparing a dispersion (latex) of resin particles containing a release agent by polymerizing an aqueous dispersion of the resulting monomer solution;
(4) a salting-out / fusing step in which the obtained resin particles and the colorant are salted out / fused in an aqueous medium to obtain associated particles (toner particles);
(5) A filtration / washing step of separating the obtained associated particles from an aqueous medium and washing away the surfactant from the associated particles;
(6) Consists of a drying step of the washed associated particles,
(7) An external additive addition step of adding an external additive to the dried association particles may be included.

[Dissolution process]
The method for dissolving the release agent in the monomer is not particularly limited.

  The amount of the release agent dissolved in the monomer is such that the content of the release agent in the finally obtained toner is 1 to 30% by mass, preferably 2 to 20% by mass, more preferably 3 to 15% by mass. It is made an amount.

  An oil-soluble polymerization initiator and other oil-soluble components can also be added to the monomer solution.

[Dispersing process]
The method of dispersing the monomer solution in the aqueous medium is not particularly limited, but a method of dispersing by mechanical energy is preferable, and in particular, a surfactant having a concentration equal to or lower than the critical micelle concentration is dissolved. It is preferable to disperse oil droplets of the monomer solution in the aqueous medium to be obtained (essential aspect in the miniemulsion method).

  Here, the disperser for dispersing oil droplets by mechanical energy is not particularly limited. For example, “CLEARMIX”, ultrasonic disperser, mechanical homogenizer, Manton Gorin, pressure homogenizer, etc. Can be mentioned. The dispersed particle diameter is 10 to 1000 nm, preferably 30 to 300 nm.

[Polymerization process]
In the polymerization step, a conventionally known polymerization method (granulation polymerization method such as emulsion polymerization method, suspension polymerization method, seed polymerization method, etc.) can be basically employed.

  An example of a preferred polymerization method is a mini-emulsion method, that is, a monomer solution is dispersed in oil droplets using mechanical energy in an aqueous medium in which a surfactant having a critical micelle concentration or less is dissolved. Examples of the method include radical polymerization by adding a water-soluble polymerization initiator to the resulting dispersion.

[Salting out / fusion process]
In the salting-out / fusion process, a dispersion of a colorant is added to the dispersion of resin particles obtained by the polymerization process, and the resin particles and the colorant are salted out / fusion in an aqueous medium. Let

  In the salting-out / fusion step, the resin particles and the colorant can be fused together with the internal additive particles such as the charge control agent.

  The “aqueous medium” in the salting out / fusion step refers to a material in which the main component (50% by mass or more) is water. Examples of components other than water include organic solvents that dissolve in water, such as methanol, ethanol, isopropanol, butanol, acetone, methyl ethyl ketone, and tetrahydrofuran. Among these, alcohol-based organic solvents such as methanol, ethanol, isopropanol, and butanol, which are organic solvents that do not dissolve the resin, are particularly preferable.

  The colorant used in the salting out / fusion process can be prepared by dispersing the colorant in an aqueous medium. The dispersion treatment of the colorant is performed in a state where the surfactant concentration is set to a critical micelle concentration (CMC) or more in water.

  The disperser used for the dispersion treatment of the colorant is not particularly limited. Examples thereof include a medium type dispersing machine such as a diamond fine mill. Moreover, as a surfactant used, the same thing as the above-mentioned surfactant can be mentioned.

  The colorant (particles) may be surface-modified. In the surface modification method of the colorant, the colorant is dispersed in a solvent, the surface modifier is added to the dispersion, and the system is reacted by raising the temperature. After completion of the reaction, the colorant is separated by filtration, washed and filtered with the same solvent, and dried to obtain a colorant (pigment) treated with the surface modifier.

  In the salting-out / fusion method, a salting-out agent composed of an alkali metal salt and / or an alkaline earth metal salt or the like is added as a flocculant having a critical coagulation concentration or more to water in which resin particles and a colorant are present. Then, it is a step of performing fusion at the same time as the salting-out proceeds by heating above the glass transition point of the resin particles. In this step, an organic solvent that is infinitely soluble in water may be added.

  Here, the alkali metal salt and the alkaline earth metal salt which are salting-out agents include lithium, potassium, sodium and the like as the alkali metal, and examples of the alkaline earth metal include magnesium, calcium, strontium and barium. Preferably, potassium, sodium, magnesium, calcium, and barium are used. Examples of the salt include chlorine salt, bromine salt, iodine salt, carbonate salt, sulfate salt and the like.

  Furthermore, examples of the organic solvent infinitely soluble in water include methanol, ethanol, 1-propanol, 2-propanol, ethylene glycol, glycerin, acetone, etc., but methanol, ethanol, 1-propanol having 3 or less carbon atoms. 2-propanol is preferable, and 2-propanol is particularly preferable.

  In the salting-out / fusion process, it is preferable to shorten the time for which the salting-out agent is left after adding the salting-out agent (time until heating is started) as short as possible. That is, after the salting-out agent is added, it is preferable to start heating the dispersion of the resin particles and the colorant as quickly as possible so that the temperature is equal to or higher than the glass transition temperature of the resin particles.

  The reason for this is not clear, but the agglomeration state of the particles fluctuates depending on the standing time after salting out, the particle size distribution becomes unstable, and the surface property of the fused toner fluctuates. Will occur.

  The time (starting time) until the heating is started is usually within 30 minutes, preferably within 10 minutes.

  Although the temperature which adds a salting-out agent is not specifically limited, It is preferable that it is below the glass transition temperature of a resin particle.

  Further, in the salting out / fusion step, it is necessary to quickly raise the temperature by heating, and the rate of temperature rise is preferably 1 ° C./min or more. The upper limit of the heating rate is not particularly limited, but is preferably 15 ° C./min or less from the viewpoint of suppressing the generation of coarse particles due to rapid salting out / fusion.

  Furthermore, after the dispersion of the resin particles and the colorant reaches a temperature equal to or higher than the glass transition temperature, it is important to keep salting out / fusion by maintaining the temperature of the dispersion for a certain time. Thereby, the growth of toner particles (aggregation of resin particles and colorant) and fusion (disappearance of the interface between particles) can be effectively advanced, and the durability of the finally obtained toner is improved. be able to.

  Further, after the growth of the associated particles is stopped, the fusion by heating may be continued.

[Filtering and washing process]
In this filtration / washing step, a filtration treatment for filtering the toner particles from the dispersion of toner particles obtained in the above step, and a surfactant or salt from the filtered toner particles (cake-like aggregate). A cleaning process for removing deposits such as a depositing agent is performed.

  Here, the filtration method is not particularly limited, such as a centrifugal separation method, a vacuum filtration method using Nutsche or the like, a filtration method using a filter press or the like.

[Drying process]
This step is a step of drying the washed toner particles.

  Examples of dryers used in this process include spray dryers, vacuum freeze dryers, vacuum dryers, etc., stationary shelf dryers, mobile shelf dryers, fluidized bed dryers, rotary dryers It is preferable to use a stirring dryer or the like.

  The moisture content of the dried toner particles is preferably 2% by mass or less, and more preferably 1.5% by mass or less.

  In addition, when the toner particles that have been dried are aggregated due to weak interparticle attraction, the aggregate may be crushed. Here, as the crushing treatment apparatus, a mechanical crushing apparatus such as a jet mill, a Henschel mixer, a coffee mill, or a food processor can be used.

[External additive addition process]
This step is a step of adding an external additive to the dried toner particles.

  Examples of the apparatus used for adding the external additive include various known mixing apparatuses such as a Turbuler mixer, a Henschel mixer, a Nauter mixer, and a V-type mixer.

  Further, in the toner according to the present invention, the toner having a particle diameter of 0.7 × (Dp50) or less is 8% by number or less. In order to adjust the particle size distribution within this range, it is preferable to narrow the temperature control at the salting-out / fusion stage. Specifically, the temperature is raised as quickly as possible, that is, the temperature is raised faster. As this condition, it is shown in the above-mentioned conditions. The time until the temperature rise is less than 30 minutes, preferably less than 10 minutes, and the temperature rise rate is preferably 1 to 15 ° C./min.

  The toner according to the present invention may contain materials capable of imparting various functions as toner materials in addition to the colorant and the release agent. Specific examples include charge control agents. These components can be added simultaneously with the resin particles and the colorant in the salting-out / fusion step described above, and can be added by various methods such as a method included in the toner and a method of adding to the resin particles themselves.

  Similarly, various known charge control agents and those that can be dispersed in water can be used. Specific examples include nigrosine dyes, naphthenic acid or higher fatty acid metal salts, alkoxylated amines, quaternary ammonium salt compounds, azo metal complexes, salicylic acid metal salts or metal complexes thereof.

  The water content of the toner according to the present invention is 0.1 to 2.0% by mass. The water content of the toner can be adjusted by the following method.

Specific toner moisture content adjustment method;
1) Increasing the hydrophobic component of the toner, particularly its binder resin. Among the constituent components of the binder resin, a strongly hydrophobic styrene component is made to occupy 50% by mass or more of all monomers. Particularly preferably, it is 60% or more, more preferably 70% or more.

  2) Lower the moisture content of the toner external additive. For this purpose, as described later, it is effective to increase the degree of hydrophobicity of the external additive. It is desirable to use an external additive having a hydrophobicity of 60 or more.

  3) It is an effective method to increase the amount of nonpolar release agent present on the surface. For this purpose, it is particularly preferable to use a polyolefin-based wax. In order to increase the amount of polyolefin present on the surface, a method of using a mechanical pulverizer and applying frictional heat during pulverization to bleed out the toner surface is used. is there.

  4) Adjust the amount of carboxylic acid on the toner surface.

Range of water content The toner according to the present invention has a water content of 0.1 to 2.0% by mass in an environment of 30 ° C. and 80% RH (relative humidity). More preferably, it is 0.2-1.8 mass%.

Measuring method of moisture content of toner The toner is placed in a Fischer sample bottle and left in an environment of 30 ° C. and 80% RH for 72 hours while being opened. After standing, seal the cap and measure by the Karl Fischer method. The measuring device is Hiranuma type automatic trace moisture measuring device AQS-724, and the measurement conditions are a vaporization temperature of 110 ° C. and a vaporization time of 25 seconds.

<Developer>
The toner according to the present invention may be used as a one-component developer or a two-component developer.

  When used as a one-component developer, a non-magnetic one-component developer or a magnetic one-component developer containing about 0.1 to 0.5 μm of magnetic particles in the toner can be used. be able to.

  Further, it can be mixed with a carrier and used as a two-component developer. In this case, conventionally known materials such as metals such as iron, ferrite and magnetite, and alloys of these metals with metals such as aluminum and lead can be used as the magnetic particles of the carrier. Ferrite particles are particularly preferable. The magnetic particles have a 50% volume particle diameter (Dv50) of 15 to 100 μm, more preferably 25 to 80 μm.

  The 50% volume particle size (Dv50) of the carrier is typically measured by a laser diffraction particle size distribution measuring device “HELOS” (manufactured by SYMPATEC) equipped with a wet disperser. Can do.

  The carrier is preferably a carrier in which magnetic particles are further coated with a resin, or a so-called resin dispersion type carrier in which magnetic particles are dispersed in a resin. The resin composition for coating is not particularly limited, and for example, olefin resin, styrene resin, styrene-acrylic resin, silicone resin, ester resin, or fluorine-containing polymer resin is used. In addition, the resin for constituting the resin-dispersed carrier is not particularly limited, and a known resin can be used. For example, a styrene-acrylic resin, a polyester resin, a fluorine resin, a phenol resin, or the like is used. be able to.

  The organic photoreceptor according to the present invention will be described. The organic photoreceptor used in the present invention preferably has a photosensitive layer through an intermediate layer containing inorganic particles having a number average primary particle size of 3 to 200 nm in a binder resin on a conductive support.

  When the organic photoreceptor has the above-described configuration, it is possible to prevent the occurrence of fogging and the density defect at the tip, which are likely to occur due to the counter development method, and provide a high-quality digital image or color image.

  Hereinafter, the constitution of the organic photoreceptor according to the present invention will be described.

  In the present invention, the organic photoconductor means an electrophotographic photoconductor constituted by providing an organic compound with at least one of a charge generation function and a charge transport function essential to the configuration of the electrophotographic photoconductor. All known organic photoconductors such as a photoconductor composed of an organic charge generating material or an organic charge transport material, a photoconductor composed of a polymer complex with a charge generating function and a charge transport function are contained.

  The structure of the photoreceptor according to the present invention is preferably a structure in which a charge generation layer and a charge transport layer are sequentially laminated as a photosensitive layer on a conductive support. Furthermore, it is preferable to provide an intermediate layer between the conductive support and the photosensitive layer. If necessary, a surface protective layer may be further formed on the photosensitive layer.

  Preferable specific examples of the layer structure of the organic photoreceptor according to the present invention are described below.

Conductive Support The conductive support used for the photoreceptor may be either a sheet or a cylinder, but a cylindrical conductive support is preferred for designing an image forming apparatus compactly. .

  Cylindrical conductive support means a cylindrical support necessary for forming an endless image by rotating. Conductivity is within a range of 0.1 mm or less in straightness and 0.1 mm or less in deflection. A support is preferred. Exceeding the range of straightness and shake makes it difficult to form a good image.

As the conductive material, a metal drum such as aluminum or nickel, a plastic drum deposited with aluminum, tin oxide, indium oxide or the like, or a paper / plastic drum coated with a conductive substance can be used. The conductive support preferably has a specific resistance of 10 ³ Ωcm or less at room temperature. As the conductive support, an aluminum support is most preferable. As the aluminum support, one in which components such as manganese, zinc, magnesium and the like are mixed in addition to the main component aluminum is also used.

  Further, in the organic photoreceptor according to the present invention, the effect is great when the outer diameter of the cylindrical support is 20 to 80 mm. In the case of a cylindrical support having an outer diameter of 20 to 80 mm, the surface linear velocity of the photoconductor in the image forming process tends to be high, and the tip portion density tends to be lowered and fogging tends to occur in the counter development method.

Intermediate Layer The organic photoreceptor according to the present invention is provided with an intermediate layer between the conductive support and the photosensitive layer. The intermediate layer contains inorganic particles having a number average primary particle size of 3 to 200 nm in the binder resin. By having a structure in which inorganic particles are included in the binder resin of the intermediate layer, the blocking property of free carriers (electrons and holes entering from the conductive support) from the conductive support is improved. It is possible to prevent the occurrence of fogging, increase the developability, prevent the lowering of the tip density, and obtain an electrophotographic image having a sufficient image density.

The inorganic particles used in the intermediate layer according to the present invention are titanium oxide (TiO ₂ ), zinc oxide (ZnO), tin oxide (SnO ₂ ), zirconium oxide, cerium oxide, iron oxide, aluminum oxide, tungsten oxide, bismuth oxide. Metal oxides such as silicon carbide and titanium carbide, metal carbides such as silicon carbide and titanium carbide, titanates such as strontium titanate, calcium titanate and barium titanate, carbonates such as calcium carbonate, metal nitrides such as aluminum nitride, Sulfates such as barium sulfate, copper sulfate, and zinc sulfate are also used.

  Among these inorganic particles, the inorganic particles preferably used in the present invention are preferably N-type semiconductor particles.

  N-type semiconductor particles mean particles whose main charge carriers are electrons. That is, since the main charge carrier is an electron, the intermediate layer containing the N-type semiconductor particles in the insulating binder efficiently blocks hole injection from the conductive support, and the photosensitive layer. It has a property of exhibiting transportability with respect to electrons from.

As the N-type semiconductor particles, titanium oxide (TiO ₂ ) and zinc oxide (ZnO) are preferable, and titanium oxide is particularly preferably used.

  As the N-type semiconductor particles, fine particles having a number average primary particle diameter in the range of 3.0 to 200 nm are used. Particularly, 5 nm to 100 nm is preferable. The number average primary particle diameter is a measured value as the average diameter in the ferret direction by image analysis by magnifying fine particles 10,000 times by transmission electron microscope observation, randomly observing 100 particles as primary particles. N-type semiconducting particles having a number average primary particle size of less than 3.0 nm are difficult to uniformly disperse in the intermediate layer binder, and easily form aggregated particles. Occurs and fog is likely to occur. On the other hand, N-type semiconducting particles having a number average primary particle size larger than 200 nm tend to form large irregularities on the surface of the intermediate layer, and the tip concentration tends to decrease through these large irregularities. Further, the N-type semiconducting particles having a number average primary particle size of more than 200 nm are likely to precipitate in the dispersion and easily generate aggregates. As a result, the tip concentration tends to decrease.

  The titanium oxide particles have anatase, rutile, brookite, and amorphous forms as crystal forms. Among them, the rutile form titanium oxide pigment or the anatase form titanium oxide pigment has a rectifying property of charge passing through the intermediate layer. In other words, the electron mobility is increased, the charging potential is stabilized, the residual potential is prevented from increasing, and the generation of the transfer memory can be prevented.

  N-type semiconductive particles are preferably surface-treated with a polymer containing methylhydrogensiloxane units. The molecular weight of the polymer containing the methyl hydrogen siloxane unit is 1000 to 20000, and the surface treatment effect is high. As a result, the rectifying property of the N-type semiconductor particles is improved, and the N-type semiconductor particles are contained. By using the intermediate layer, the occurrence of black spots is prevented and there is an effect in producing a good halftone image.

The polymer containing a methylhydrogensiloxane unit is preferably a copolymer of a structural unit of-(HSi (CH ₃ ) O)-and a structural unit other than this (other siloxane unit). As other siloxane units, dimethylsiloxane units, methylethylsiloxane units, methylphenylsiloxane units, diethylsiloxane units, and the like are preferable, and dimethylsiloxane is particularly preferable. The proportion of methylhydrogensiloxane units in the copolymer is 10 to 99 mol%, preferably 20 to 90 mol%.

  The methylhydrogensiloxane copolymer may be any of a random copolymer, a block copolymer, a graft copolymer, etc., but a random copolymer and a block copolymer are preferred. In addition to methylhydrogensiloxane, the copolymerization component may be one component or two or more components.

  Further, the N-type semiconductive particles may be those surface-treated with a reactive organosilicon compound represented by the following formula.

(R) _n -Si- (X) _4-n
(In the above formula, Si represents a silicon atom, R represents an organic group in which carbon is directly bonded to the silicon atom, X represents a hydrolyzable group, and n represents an integer of 0 to 3).
In the organosilicon compound represented by the above formula, the organic group in which carbon is directly bonded to the silicon represented by R includes alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl and dodecyl, phenyl , Aryl groups such as tolyl, naphthyl and biphenyl, epoxy-containing groups such as γ-glycidoxypropyl and β- (3,4-epoxycyclohexyl) ethyl, γ-acryloxypropyl and γ-methacryloxypropyl ( (Meth) acryloyl group, hydroxyl group such as γ-hydroxypropyl, 2,3-dihydroxypropyloxypropyl, vinyl group such as vinyl and propenyl, mercapto group such as γ-mercaptopropyl, γ-aminopropyl, N-β Amino-containing groups such as (aminoethyl) -γ-aminopropyl, γ-chloropropyl, 1,1, - trifluoride Oro propyl, nonafluorohexyl, halogen-containing groups such as perfluorooctylethyl, other nitro, and cyano-substituted alkyl group. Examples of the hydrolyzable group for X include alkoxy groups such as methoxy and ethoxy, halogen groups, and acyloxy groups.

  Moreover, the organosilicon compound represented by the above formula may be used alone or in combination of two or more.

  Further, in the case of a specific compound of an organosilicon compound represented by the above formula and n is 2 or more, a plurality of R may be the same or different. Similarly, when n is 2 or less, the plurality of Xs may be the same or different. Moreover, when using 2 or more types of organosilicon compounds represented by the above formula, R and X may be the same or different between the respective compounds.

  Further, prior to the surface treatment of the methylhydrogensiloxane copolymer or the reactive organosilicon compound, the N-type semiconductive particles may be subjected to an inorganic surface treatment such as alumina or silica.

  In addition, although the above-mentioned treatment of alumina and silica may be performed simultaneously, it is preferable to perform the alumina treatment first and then the silica treatment. Further, the amount of treatment of alumina and silica when treating alumina and silica is preferably higher than that of alumina.

  The surface treatment of the N-type semiconductive fine particles such as titanium oxide with a metal oxide such as alumina, silica or zirconia can be performed by a wet method. For example, N-type semiconductive particles subjected to silica or alumina surface treatment can be prepared as follows.

  When titanium oxide particles are used as the N-type semiconductive particles, titanium oxide particles (number average primary particle size: 50 nm) are dispersed in water at a concentration of 50 to 350 g / L to form an aqueous slurry. Add acid salt or water-soluble aluminum compound. Thereafter, alkali or acid is added for neutralization, and silica or alumina is precipitated on the surface of the titanium oxide particles. Subsequently, filtration, washing, and drying are performed to obtain the target surface-treated titanium oxide. When sodium silicate is used as the water-soluble silicate, it can be neutralized with an acid such as sulfuric acid, nitric acid or hydrochloric acid. On the other hand, when aluminum sulfate is used as the water-soluble aluminum compound, it can be neutralized with an alkali such as sodium hydroxide or potassium hydroxide.

  The intermediate layer coating solution prepared for forming the intermediate layer used in the present invention is composed of a binder resin, a dispersion solvent and the like in addition to the N-type semiconductive particles such as the surface-treated titanium oxide.

  The ratio of the N-type semiconductive particles in the intermediate layer is preferably 1.0 to 2.0 times in terms of the volume ratio of the intermediate layer to the binder resin (when the volume of the binder resin is 1). By using such high-density N-type semiconductor particles in the intermediate layer, the rectifying property of the intermediate layer is increased, and even if the film thickness is increased, there is no increase in residual potential or transfer memory. Can be effectively prevented, and a good organic photoreceptor with small potential fluctuation can be formed. Further, such an intermediate layer preferably uses 100 to 200 parts by volume of N-type semiconductive particles with respect to 100 parts by volume of the binder resin.

  On the other hand, the binder resin in which these particles are dispersed to form the layer structure of the intermediate layer is preferably a polyamide resin in order to obtain good dispersibility of the particles, but the polyamide resin shown below is particularly preferable.

  That is, a polyamide resin having a heat of fusion of 0 to 40 J / g and a water absorption of 5% by mass or less is preferable for the intermediate layer. The heat of fusion is more preferably 0 to 30 J / g, and most preferably 0 to 20 J / g. On the other hand, when the water absorption exceeds 5% by mass, the moisture content in the intermediate layer increases, the rectification property of the intermediate layer decreases, black spots tend to occur, and the halftone image tends to deteriorate. The water absorption is more preferably 4% by mass or less.

  The heat of fusion of the resin is measured by DSC (Differential Scanning Calorimetry). However, if the same measurement value as the DSC measurement value is obtained, the DSC measurement method is not particular. The heat of fusion is determined from the endothermic peak area when the DSC temperature rises.

  On the other hand, the water absorption rate of the resin is determined by mass change by the water immersion method or by the Karl Fischer method.

  The binder resin for the intermediate layer is preferably an alcohol-soluble polyamide resin. As the binder resin for the intermediate layer of the organic photoreceptor, a resin having excellent solvent solubility is required in order to form the intermediate layer with a uniform film thickness. As such an alcohol-soluble polyamide resin, a copolymerized polyamide resin or a methoxymethylated polyamide resin composed of a chemical structure with few carbon chains between amide bonds such as 6-nylon described above is known. This resin has a high water absorption rate, and the intermediate layer using such a polyamide tends to be highly environment-dependent. As a result, for example, charging characteristics and sensitivity under high temperature and high humidity and low temperature and low humidity are likely to change. Black spots are likely to occur and halftone images are likely to deteriorate.

  Alcohol-soluble polyamide resin improves the above-mentioned drawbacks and improves the disadvantages of conventional alcohol-soluble polyamide resins by giving the characteristics of heat of fusion 0-40 J / g and water absorption of 5% by mass or less. Even if the external environment changes or even if the organic photoreceptor is used continuously for a long time, a good electrophotographic image can be obtained.

  Hereinafter, the alcohol-soluble polyamide resin having a heat of fusion of 0 to 40 J / g and a water absorption of 5% by mass or less will be described.

  The alcohol-soluble polyamide resin is preferably a polyamide resin containing a repeating unit structure having 7 to 30 carbon atoms between amide bonds in an amount of 40 to 100 mol% of the entire repeating unit structure.

  Here, a repeating unit structure having 7 to 30 carbon atoms between amide bonds will be described. The repeating unit structure means an amide bond unit forming a polyamide resin. This is because a polyamide resin (type A) formed by condensation of a compound having a repeating unit structure having both an amino group and a carboxylic acid group, and a polyamide resin (type B) formed by condensation of a diamino compound and a dicarboxylic acid compound. ) In both examples.

  That is, the repeating unit structure of type A is represented by the general formula (1), and the carbon number contained in X is the carbon number of the amide bond unit in the repeating unit structure. On the other hand, the repeating unit structure of Type B is represented by the general formula (2), and the number of carbons contained in Y and the number of carbons contained in Z are the number of amide bond units in the repeating unit structure.

In general formula (1), R ₁ is a hydrogen atom, a substituted or unsubstituted alkyl group, X is a substituted or unsubstituted alkylene group, a group containing a divalent cycloalkane, a divalent aromatic group, and these A mixed structure is shown, and l is a natural number.

In general formula (2), R ₂ and R ₃ are each hydrogen atom, a substituted or unsubstituted alkyl group, Y and Z are each substituted or unsubstituted alkylene group, a group containing a divalent cycloalkane, divalent And m and n are natural numbers.

  As described above, the repeating unit structure having 7 to 30 carbon atoms includes a substituted or unsubstituted alkylene group, a group containing a divalent cycloalkane, a divalent aromatic group, and a chemical structure having a mixed structure thereof. Among them, a chemical structure having a group containing a divalent cycloalkane is preferable.

  The polyamide resin has 7 to 30 carbon atoms between amide bonds in the repeating unit structure, preferably 9 to 25, more preferably 11 to 20. The proportion of the repeating unit structure having 7 to 30 carbon atoms between amide bonds in the entire repeating unit structure is 40 to 100 mol%, preferably 60 to 100 mol%, more preferably 80 to 100 mol%.

  When the carbon number is less than 7, the hygroscopicity of the polyamide resin is large, the electrophotographic characteristics, particularly the humidity dependency of the potential during repeated use is large, and image defects such as black spots are likely to occur, and the halftone image is Easy to deteriorate. If it is larger than 30, the dissolution of the polyamide resin in the coating solvent becomes worse, and it is not suitable for forming a coating film of the intermediate layer.

  Further, when the ratio of the repeating unit structure having 7 to 30 carbon atoms between amide bonds to the entire repeating unit structure is smaller than 40 mol%, the above effect is reduced.

  Preferred polyamide resins include polyamides having a repeating unit structure represented by the following general formula (3).

In General Formula (3), Y ₁ represents a group containing a divalent alkyl-substituted cycloalkane, Z ₁ represents a methylene group, m represents 1 to 3, and n represents 3 to 20.

In the general formula (3), the group containing a divalent alkyl-substituted cycloalkane of Y ₁ preferably has the following chemical structure. That is, the polyamide resin in which Y ₁ has the following chemical structure has a remarkable effect of preventing the occurrence of a black spot or a decrease in the density of the front end of a halftone image.

In the above chemical structure, A represents a single bond and an alkylene group having 1 to 4 carbon atoms, R ₄ represents a substituent, represents an alkyl group, and p represents a natural number of 1 to 5. However, the plurality of R ₄ may be the same or different.

  Specific examples of the polyamide resin include the following examples.

  In the above specific examples, “%” in parentheses indicates the ratio (mol%) of the repeating unit structure having 7 or more carbon atoms between amide bonds in the repeating unit structure.

  Among the above specific examples, N-1 to N-4 polyamide resins having a repeating unit structure of the general formula (3) are particularly preferable.

  The molecular weight of the polyamide resin is preferably 5,000 to 80,000, more preferably 10,000 to 60,000 in terms of number average molecular weight. When the number average molecular weight is 5,000 or less, the uniformity of the film thickness of the intermediate layer is deteriorated, and the effects of the present invention are not sufficiently exhibited. On the other hand, if it is larger than 80,000, the solvent solubility of the resin is likely to be reduced, aggregated resin is likely to be generated in the intermediate layer, and the tip portion density is likely to be reduced in black spots and halftone images.

  A part of the polyamide resin is already available on the market. For example, the polyamide resin is sold under the trade names such as Vestamelt X1010 and X4685 manufactured by Daicel Degussa Co., Ltd., and can be produced by a general synthesis method of polyamide. However, an example of a synthesis example is given below.

Synthesis of exemplified polyamide resin (N-1) 215 parts by mass of lauryl lactam, 3-aminomethyl-3,5,5-trimethylcyclohexylamine in a polymerization kettle equipped with a stirrer, nitrogen, nitrogen introduction tube, thermometer, dehydration tube, etc. 112 parts by mass, 153 parts by mass of 1,12-dodecanedicarboxylic acid and 2 parts by mass of water were mixed and reacted for 9 hours while distilling water under heating and pressure. When the polymer was taken out and the copolymer composition was determined by C ¹³ -NMR, it coincided with the composition of N-1. The melt flow index (MFI) of the synthesized copolymer was 5 g / 10 min under the condition of (230 ° C./2.16 kg).

  As the solvent for dissolving the polyamide resin and preparing the coating solution, alcohols having 2 to 4 carbon atoms such as ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, t-butanol, sec-butanol are preferable, It is excellent in the solubility of polyamide and the coating property of the prepared coating solution. These solvents are 30 to 100% by mass, preferably 40 to 100% by mass, and more preferably 50 to 100% by mass in the total solvent. Examples of co-solvents that can be used in combination with the above-mentioned solvent to obtain preferable effects include methanol, benzyl alcohol, toluene, methylene chloride, cyclohexanone, and tetrahydrofuran.

  The thickness of the intermediate layer according to the present invention is preferably 0.3 to 10 μm. If the film thickness of the intermediate layer is less than 0.5 μm, the density of the tip portion tends to decrease in black spots and halftone images, and if it exceeds 10 μm, the residual potential increases and transfer memory tends to occur, and the sharpness deteriorates. Cheap. As for the film thickness of an intermediate | middle layer, 0.5-5 micrometers is more preferable.

Moreover, it is preferable that the said intermediate | middle layer is an insulating layer substantially. Here, the insulating layer has a volume resistance of 1 × 10 ⁸ or more. The volume resistance of the intermediate layer and the protective layer according to the present invention is preferably 1 × 10 ⁸ to 10 ¹⁵ Ω · cm, more preferably 1 × 10 ⁹ to 10 ¹⁴ Ω · cm, and still more preferably 2 × 10 ⁹ to 1 × 10 ¹³ Ω · cm. The volume resistance can be measured as follows.

  Measurement conditions: According to JIS: C2318-1975.

Measuring instrument: Hiresta IP manufactured by Mitsubishi Yuka
Measurement conditions: Measurement probe HRS
Applied voltage: 500V
Measurement environment: 30 ± 2 ℃, 80 ± 5RH%
If the volume resistance is less than 1 × 10 ⁸ , the charge blocking property of the intermediate layer decreases, the occurrence of black spots increases, the potential holding property of the organic photoreceptor deteriorates, and good image quality cannot be obtained. On the other hand, if it is greater than 10 ¹⁵ Ω · cm, the residual potential tends to increase in repeated image formation, and good image quality cannot be obtained.

  As a solvent for preparing the coating solution for forming the intermediate layer, any known organic solvent such as alcohol, aromatic, halogenated hydrocarbon, ketone, ketone alcohol, ether, ester, etc. Can be selected.

  For example, methanol, ethanol, n-propanol, iso-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, ethyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, Usual organic solvents such as methylene chloride, chloroform, chlorobenzene, and toluene can be used.

  Moreover, the solvent used for these dispersion | distribution can be used individually or in mixture of 2 or more types. When mixing, any solvent can be used as long as it can dissolve the binder resin as the mixed solvent.

  As a method for dispersing the inorganic particles surface-treated with a coupling agent or the like in the binder resin, methods such as a roll mill, a ball mill, a vibrating ball mill, an attritor, a sand mill, a colloid mill, and a paint shaker can be used. Furthermore, as an application method used when providing this undercoat layer, a usual method such as a blade coating method, a wire bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, or a curtain coating method is used. Can be used.

Photosensitive layer Charge generation layer (CGL)
The charge generation layer is a layer mainly composed of a charge generation material (CGM), and a binder resin may be used as necessary.

  A known material can be used as the charge generating substance. For example, phthalocyanine pigments such as metal phthalocyanine and metal-free phthalocyanine, azulenium salt pigments, squaric acid methine pigments, azo pigments having a carbazole skeleton, azo pigments having a triphenylamine skeleton, azo pigments having a diphenylamine skeleton, dibenzothiophene skeleton Azo pigments having fluorenone skeleton, azo pigments having oxadiazole skeleton, azo pigments having bis-stilbene skeleton, azo pigments having distyryl oxadiazole skeleton, azo pigments having distyrylcarbazole skeleton, perylene Pigments, anthraquinone or polycyclic quinone pigments, quinoneimine pigments, diphenylmethane and triphenylmethane pigments, benzoquinone and naphthoquinone pigments, cyanine and azomethine pigments, Goido based pigments, and bisbenzimidazole pigments. These charge generation materials can be used alone or as a mixture of two or more.

  When the phthalocyanine pigment is used in the CGM, the effect of the present invention is remarkably exhibited. Organic photoreceptors using titanyl phthalocyanine pigments, gallium phthalocyanine pigments, etc. as charge generation materials tend to vary in potential characteristics. However, when the intermediate layer according to the present invention is used, the potential variation is improved and the counter development method is used. Even with this image forming method, it is possible to prevent the occurrence of fogging and to prevent the occurrence of a partial decrease in density at the leading edge of the image.

  When a binder is used as the CGM dispersion medium in the charge generation layer, a known resin can be used as the binder, but the most preferred resins include formal resin, butyral resin, silicone resin, silicone-modified butyral resin, phenoxy resin, and the like. Can be mentioned. The ratio of the binder resin to the charge generating material is preferably 20 to 600 parts by mass with respect to 100 parts by mass of the binder resin. By using these resins, the increase in residual potential associated with repeated use can be minimized. The thickness of the charge generation layer is preferably 0.3 μm to 2 μm.

Charge transport layer (CTL)
The charge transport layer is a layer intended to hold a charged charge and to couple the charge generated and separated in the charge generation layer by exposure to the charged charge that has been held. In order to achieve the purpose of holding the charged charge, it is required that the electric resistance is high. Further, in order to achieve the purpose of obtaining a high surface potential with the charged charge that has been held, it is required that the dielectric constant is small and the charge mobility is good.

  The charge transport layer for satisfying these requirements is composed of a charge transport material (CTM) and a binder resin used as necessary. Such a charge transport layer can be formed by dissolving or dispersing these charge transport materials and a binder resin in an appropriate solvent, and applying and drying them. If necessary, an appropriate amount of additives such as a plasticizer, an antioxidant, and a leveling agent can be added to the charge transport layer in addition to the charge transport material and the binder resin.

  Examples of the charge transporting material include a hole transporting material and an electron transporting material, and the hole transporting material is preferable in the layer structure of the organic photoreceptor according to the present invention.

  The charge transport layer contains a charge transport material (CTM) and a binder resin that disperses and forms a CTM. Other substances may contain additives such as antioxidants as necessary.

  As the charge transport material, a known hole transport property (P-type) charge transport material (CTM) can be used. For example, a triphenylamine derivative, a hydrazone compound, a styryl compound, a benzidine compound, a butadiene compound, or the like can be used. These charge transport materials are usually dissolved in a suitable binder resin to form a layer.

  As the charge transport material according to the present invention, those having relatively high charge mobility, good dispersibility in the binder, and stable potential characteristics are preferable, and in particular, a compound represented by the following general formula (4) is preferable. .

(In the general formula (4), R ₁ represents a hydrogen atom, an alkyl group, an alkoxy group or a halogen atom, and R ₂ and R ₃ represent an alkyl group, a substituted or unsubstituted aralkyl group or a substituted or unsubstituted aryl group. R ₂ and R ₃ may be the same or different, R ₄ and R _{5 each} represent a hydrogen atom, a lower alkyl group or a substituted or unsubstituted aryl group, and Ar represents a substituted or unsubstituted aryl group And Ar and R ₅ may combine to form a ring.)
Specific examples of the compound of the general formula (4) are shown below.

  The binder resin used for the charge transport layer (CTL) may be either a thermoplastic resin or a thermosetting resin. For example, polystyrene, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, polyvinyl butyral resin, epoxy resin, polyurethane resin, phenol resin, polyester resin, alkyd resin, polycarbonate resin, silicone resin, melamine resin, and these resins A copolymer resin containing two or more of the repeating unit structures. In addition to these insulating resins, high molecular organic semiconductors such as poly-N-vinylcarbazole can be used. Of these, polycarbonate resins are most preferred because of their low water absorption and good CTM dispersibility and electrophotographic characteristics.

  The ratio of the binder resin to the charge transport material is preferably 50 to 200 parts by mass with respect to 100 parts by mass of the binder resin. The total thickness of the charge transport layer is preferably 20 μm or less, and more preferably 10 to 16 μm. When the film thickness exceeds 20 μm, the absorption and scattering of the short wavelength laser in the charge transport layer increase, and the sharpness tends to decrease and the residual potential tends to increase.

  The surface layer of the photoreceptor according to the present invention preferably contains an antioxidant. The surface layer is easily oxidized by an active gas such as NOx or ozone during charging of the photoconductor, and image blur is likely to occur. However, the presence of an antioxidant can prevent image blur. Typical examples of the antioxidants are those that prevent the action of oxygen under conditions of light, heat, discharge, etc. on auto-oxidizing substances present in the organic photoreceptor or on the surface of the organic photoreceptor, It is a substance that has the property of inhibiting. Typical examples include the following compound groups.

  Further, it is preferable that the uppermost layer of the photoreceptor according to the present invention contains a fluorine-containing resin fine particle. By including the fluorine-containing resin fine particles in the resurface layer, the transferability of the toner image formed on the surface of the photoreceptor to a transfer material or the like is improved, and the reproducibility of the dot image is improved.

  Solvents or dispersion media used to form layers such as intermediate layers, charge generation layers, and charge transport layers include n-butylamine, diethylamine, ethylenediamine, isopropanolamine, triethanolamine, triethylenediamine, N, N-dimethylformamide, acetone , Methyl ethyl ketone, methyl isopropyl ketone, cyclohexanone, benzene, toluene, xylene, chloroform, dichloromethane, 1,2-dichloroethane, 1,2-dichloropropane, 1,1,2-trichloroethane, 1,1,1-trichloroethane, trichloroethylene, Tetrachloroethane, tetrahydrofuran, dioxolane, dioxane, methanol, ethanol, butanol, isopropanol, ethyl acetate, butyl acetate, dimethyl sulfoxide, methyl cello Lube, and the like. Although this invention is not limited to these, Dichloromethane, 1, 2- dichloroethane, methyl ethyl ketone, etc. are used preferably. These solvents may be used alone or as a mixed solvent of two or more.

  A developing device (developing means) of the counter developing system will be described with reference to FIG. The developing device in FIG. 1 is a contact type two-component type developing device, but the present invention is not limited to this contact type two-component type developing device. For example, a non-contact type one-component type developing device is also employed. it can. In the developing device 102, a developing sleeve 120 (developer carrying member) in which a cylindrical magnet 121 is non-rotatably disposed in an opening of a developing container 110 containing a two-component developer is an organic photoreceptor (image carrier). The developing sleeve 120 is arranged to face the organic photosensitive member 101 rotating in the direction of the arrow, and the developing sleeve 120 rotates counterclockwise so that the developer adsorbed and held on the surface of the developing sleeve 120 and the organic photosensitive member 101 is It is transported to the opposite developing unit. The magnet 121 has a developing magnetic pole N1 on the organic photoreceptor 101 side, and the first conveying magnetic pole S3, the second conveying magnetic pole N2, the third conveying magnetic pole S2, and the second conveying magnetic pole S2 are arranged in the rotational direction of the developing sleeve 120 from the developing magnetic pole N1. 3. It has a pumping magnetic pole S1 constituting a conveying magnetic pole and a separating magnetic pole.

  The developer in the developing container 110 is attracted and held on the developing sleeve 120 by the action of the pumping pole S1 at the position (pumping position) Q on the surface of the developing sleeve 120 corresponding to the pumping magnetic pole S1 of the magnet 121, and the developing blade After the layer thickness is regulated by 122 (developer layer thickness regulating means), the developing part is reached, and a magnetic brush (developing brush) is formed by the action of the developing magnetic pole N1 in the developing part. Develop.

  The developer whose toner density is reduced by the development is held on the developing sleeve 120 and returned to the inside of the developing container 110 by the action of the first and second transport magnetic poles S3 and N2, and the third transport magnetic pole S2 and the pumping magnetic pole S1. At the position (developer dropping position) P on the surface of the developing sleeve 120 where the intermediate magnetic flux density is the smallest, it peels off from the developing sleeve 120 and falls. The developing sleeve 120 from which the developer has been peeled is adsorbed and held by the new developer at the pumping position Q as described above.

  A first agitating and conveying member 123 is installed below the developing sleeve 120 in the developing container 110, and a second agitating and conveying member 124 is further installed via a partition wall 140. These first and second agitating / conveying members 123 and 124 are of a screw type and have a helical screw blade 128 and a plate-like protrusion 130 between the blades.

  The developer having a low toner concentration peeled off from the developing sleeve 120 falls on the first stirring / conveying member 123 and is stirred and conveyed in the axial direction by the first stirring / conveying member 123 in the axial direction. This is passed to the second agitating and conveying member 124 through an opening (not shown). The second agitating / conveying member 124 conveys the developer and the toner replenished from the replenishing port 118 of the developing container 110 in a reverse rotation to the above while agitating, and an opening (not shown) at the other end of the partition wall 140. And return to the first stirring and conveying member 123 side.

A preferred configuration of the counter development method will be described. Here, the gap between the photosensitive member 101 and the developing sleeve 120 in the developing portion near the developing magnetic pole N1 in FIG. 1 is a developing gap (Dsd), and the height of the magnetic brush formed on the developing sleeve 120 by the developing magnetic pole N1. Is called the developing brush height (h).
(1) Development gap (Dsd): 0.2 to 0.6 mm
When Dsd is set to 0.2 to 0.6 mm, development is performed in a strong developing electric field, the binding force of the magnetic carrier to the developing sleeve is increased, and the magnetic carrier is prevented from being transferred to and adhered to the photoconductor. it can. In addition, since the developing electric field at the developing gap is increased, the edge effect is reduced and the developing ability is improved. Accordingly, it is possible to prevent the occurrence of thinning of the horizontal line image and white-out at the rear end (deterioration at the rear end), and improve the developability of the solid image.
(2) Depth of penetration of magnetic brush (Bsd): 0.0 to 0.8 mm, Depth of penetration of magnetic brush (Bsd) = Development brush height (h) −Development gap (Dsd)
By setting the magnetic brush biting depth to 0.0 to 0.8 mm, the pressure contact with the developer in the developing portion is reduced, and the developer is prevented from slipping through the gap between the developing sleeve 120 and the developing blade 122. The Further, it is possible to prevent the development failure of the isolated dot image and the increase in the rough feeling of the halftone image caused by the non-uniform contact of the magnetic brush. When the magnetic brush bite depth is 0 or less, that is, in a non-contact state, the density tends to decrease. When the depth is larger than 0.8 mm, the developer overflows from the nip portion, and uniform image formation cannot be expected.
(3) Peripheral speed ratio (Vs / Vopc) between the developing sleeve and the photoreceptor: 1.2 to 3.0
By setting the peripheral speed ratio of the developing sleeve to the photoreceptor to 1.2 to 3.0, high developability can be obtained. If the peripheral speed ratio is increased too much, the contact frequency of the magnetic brush on the developing sleeve with respect to the photosensitive member increases too much, and the contact state of the magnetic brush with respect to the latent photosensitive member, that is, the mechanical force becomes excessively large. Are likely to fall off, and the carrier is likely to adhere to the photoreceptor, and as a result, the brush image of the magnetic brush is formed on the toner image on the photoreceptor. On the other hand, if the peripheral speed ratio is lowered too much, the chance of contact of the magnetic brush with the photoreceptor is reduced too much, and the developability is lowered. Accordingly, when the peripheral speed ratio is smaller than 1.2, the density is lowered, and when it is larger than 3.0, there is a problem in toner scattering, carrier adhesion, or developing sleeve durability. On the other hand, by setting the peripheral speed ratio within the above range, it is possible to prevent brush eyes. Furthermore, it has the function of preventing the developing effect from becoming excessively high and enhancing the edge effect.
(4) Development bias condition The difference | V0-Vdc | between the surface potential V0 of the photosensitive member and the DC component Vdc of the developing bias applied to the developing sleeve is 100 to 300V, and the DC component Vdc of the developing bias is -300V to -650V. The AC component Vac of the developing bias is preferably 0.5 to 1.5 kV, the frequency is 3 to 9 kHz, the duty is 45 to 70% (the development-side time ratio in the rectangular wave), and the rectangular wave. That is, in a small two-component developing device having an outer diameter of the developing sleeve of φ30 mm or less and an outer diameter of the photosensitive member of φ60 mm or less, the developing nip width is reduced and the developing ability is reduced by making the developing sleeve small. The development bias condition can be improved by the development bias condition.

  Next, the process cartridge and the electrophotographic apparatus according to the present invention will be described. FIG. 2 shows a schematic configuration of an electrophotographic apparatus having a process cartridge including an organic photoreceptor.

  In FIG. 2, reference numeral 1 denotes a drum-shaped organic photoconductor (photoconductor), which is driven to rotate about a shaft C in the direction of an arrow at a predetermined peripheral speed. In the rotation process, the organic photoreceptor 1 is uniformly charged with a positive or negative predetermined potential on its peripheral surface by the charging means 2 and then output from an exposure means (not shown) such as slit exposure or laser beam scanning exposure. Exposure light 3 (exposure means) that has been emphasized and modulated in response to a time-series electrical digital image signal of target image information. In this way, electrostatic latent images corresponding to the target image information are sequentially formed on the peripheral surface of the organic photoreceptor 1.

  The formed electrostatic latent image is then developed with toner by the developing means 4 and taken out from a paper feed unit (not shown) between the organic photoreceptor 1 and the transfer means 5 in synchronization with the rotation of the organic photoreceptor 1. The toner images formed and supported on the surface of the organic photoreceptor 1 are sequentially transferred by the transfer means 5 to the fed transfer material P.

  The transfer material P that has received the transfer of the toner image is separated from the surface of the organic photoreceptor, introduced into the image fixing means 24, and subjected to image fixing to be printed out as an image formed product (print, copy).

  After the image transfer, the surface of the organic photoreceptor 1 is cleaned by removing the transfer residual toner by the cleaning unit 6, and is further subjected to a static elimination process with pre-exposure light Pex from a pre-exposure unit (not shown). Used repeatedly for image formation. When the charging unit 2 is a contact charging unit using a charging roller or the like, pre-exposure is not always necessary.

  In the present invention, among the above-mentioned components such as the organic photoreceptor 1, the charging unit 2, the developing unit 4 and the cleaning unit 6, a plurality of components are housed in a container PC and integrally combined as a process cartridge. The process cartridge may be configured to be detachable from an electrophotographic apparatus main body such as a copying machine or a laser beam printer. For example, at least one of the charging unit 2, the developing unit 4 and the cleaning unit 6 is integrally supported together with the organic photoreceptor 1 to form a cartridge, which can be attached to and detached from the apparatus body using a guide unit AN such as a rail of the apparatus body. It can be a process cartridge.

  An embodiment of an electrophotographic printer (hereinafter simply referred to as a printer) will be described as a full-color image forming apparatus to which the present invention is applied.

  FIG. 3 is a cross-sectional configuration diagram of a color image forming apparatus showing an embodiment of the present invention.

  This color image forming apparatus is called a tandem type color image forming apparatus, and includes four sets of image forming units (image forming units) 10Y, 10M, 10C, and 10Bk, an endless belt-shaped intermediate transfer body unit 7, and a feeding unit. It comprises a paper conveying means 21 and a fixing means 24. A document image reading device SC is disposed on the upper part of the main body A of the image forming apparatus.

  An image forming unit 10Y that forms a yellow image has a charging unit 2Y, an exposing unit 3Y, a developing unit 4Y, and a primary transfer unit disposed around a drum-shaped photoconductor 1Y as a first image carrier. A primary transfer roller 5Y and a cleaning means 6Y are provided. An image forming unit 10M that forms a magenta image includes a drum-shaped photoconductor 1M as a first image carrier, a charging unit 2M, an exposure unit 3M, a developing unit 4M, a primary transfer roller 5M as a primary transfer unit, It has a cleaning means 6M. An image forming unit 10C for forming a cyan image includes a drum-shaped photoconductor 1C as a first image carrier, a charging unit 2C, an exposure unit 3C, a developing unit 4C, a primary transfer roller 5C as a primary transfer unit, It has cleaning means 6C. The image forming unit 10Bk that forms a black image includes a drum-shaped photoreceptor 1Bk as a first image carrier, a charging unit 2Bk, an exposure unit 3Bk, a developing unit 4Bk, a primary transfer roller 5Bk as a primary transfer unit, and a cleaning unit. 6Bk.

  The four sets of image forming units 10Y, 10M, 10C, and 10K include charging means 2Y, 2M, 2C, and 2K that rotate around the photosensitive drums 1Y, 1M, 1C, and 1K, and image exposure means 3Y, 3M, 3C and 3K, rotating developing means 4Y, 4M, 4C and 4K, and cleaning means 5Y, 5M, 5C and 5K for cleaning the photosensitive drums 1Y, 1M, 1C and 1K.

  The image forming units 10Y, 10M, 10C, and 10K have the same configuration except that the colors of the toner images formed on the photoreceptors 1Y, 1M, 1C, and 1Bk are different, and the image forming unit 10Y is taken as an example in detail. explain.

  The image forming unit 10Y has a charging unit 2Y (hereinafter simply referred to as a charging unit 2Y or a charger 2Y), an exposure unit 3Y, a developing unit 4Y, and a cleaning unit 5Y (around a photosensitive drum 1Y as an image forming body). Hereinafter, the cleaning means 5Y or the cleaning blade 5Y) is simply disposed, and a yellow (Y) toner image is formed on the photosensitive drum 1Y. In the present embodiment, in the image forming unit 10Y, at least the photosensitive drum 1Y, the charging unit 2Y, the developing unit 4Y, and the cleaning unit 5Y are provided so as to be integrated.

  The charging unit 2Y is a unit that applies a uniform potential to the photosensitive drum 1Y. In the present embodiment, a corona discharge type charger 2Y is used for the photosensitive drum 1Y.

  The image exposure means 3Y performs exposure based on the image signal (yellow) on the photosensitive drum 1Y given a uniform potential by the charger 2Y, and forms an electrostatic latent image corresponding to the yellow image. As the exposure means 3Y, the exposure means 3Y includes an LED in which light emitting elements are arranged in an array in the axial direction of the photosensitive drum 1Y and an imaging element (trade name; Selfoc lens), or A laser optical system or the like is used.

In the image forming method of the present invention, when an electrostatic latent image is formed on a photoreceptor, it is preferable to perform image exposure using an exposure beam having a spot area of 2000 μm ² or less. Even when such small-diameter beam exposure is performed, the organic photoreceptor of the present invention can faithfully form an image corresponding to the spot area. A more preferable spot area is 100 to 1000 μm ² . As a result, an electrophotographic image having a gradation of not less than 800 dpi (dpi is the number of dots per 2.54 cm) can be achieved.

The spot area of the exposure beam is a light intensity distribution plane appearing on the cut surface when the exposure beam is cut along a plane perpendicular to the beam, and in a region where the light intensity is 1 / e ² or more of the maximum peak intensity. It means the corresponding area.

Examples of the light beam used include a scanning optical system using a semiconductor laser, and a solid state scanner such as an LED or a liquid crystal shutter. The light intensity distribution includes a Gaussian distribution and a Lorentz distribution, but 1 / e of each peak intensity. ^The area up to ² is the spot area.

  The endless belt-shaped intermediate transfer body unit 7 is an endless belt-shaped intermediate transfer body 70 (transfer medium) as a semiconductive endless belt-shaped second image carrier that is wound around a plurality of rollers and rotatably supported. ).

  Each color image formed by the image forming units 10Y, 10M, 10C, and 10Bk is sequentially transferred onto a rotating endless belt-shaped intermediate transfer body 70 by primary transfer rollers 5Y, 5M, 5C, and 5Bk as primary transfer means. Thus, a synthesized color image is formed. A transfer material (transfer medium) P as a transfer material (support for supporting the final fixed image: for example, plain paper, transparent sheet, etc.) housed in the paper feed cassette 20 is fed by the paper feeding means 21. Then, after passing through a plurality of intermediate rollers 22A, 22B, 22C, 22D, and a registration roller 23, they are conveyed to a secondary transfer roller 5b as a secondary transfer means, and are secondarily transferred onto a transfer material P to collectively transfer color images. The The transfer material P onto which the color image has been transferred is subjected to fixing processing by the fixing unit 24, is sandwiched between paper discharge rollers 25, and is placed on a paper discharge tray 26 outside the apparatus. Here, the transfer medium refers to a transfer medium for a toner image on a photosensitive member such as an intermediate transfer member or a transfer material.

  On the other hand, after the color image is transferred to the transfer material P by the secondary transfer roller 5b as the secondary transfer means, the residual toner is removed by the cleaning means 6b from the endless belt-shaped intermediate transfer body 70 in which the transfer material P is separated by curvature. The

  During the image forming process, the primary transfer roller 5Bk is always in pressure contact with the photoreceptor 1Bk. The other primary transfer rollers 5Y, 5M, and 5C are in pressure contact with the corresponding photoreceptors 1Y, 1M, and 1C, respectively, only during color image formation.

  The secondary transfer roller 5b is brought into pressure contact with the endless belt-shaped intermediate transfer body 70 only when the transfer material P passes through the secondary transfer roller 5b.

  Further, the housing 8 can be pulled out from the apparatus main body A through the support rails 82L and 82R.

  The housing 8 includes image forming units 10Y, 10M, 10C, and 10Bk and an endless belt-shaped intermediate transfer body unit 7.

  The image forming units 10Y, 10M, 10C, and 10Bk are arranged in tandem in the vertical direction. An endless belt-shaped intermediate transfer body unit 7 is disposed on the left side of the photoreceptors 1Y, 1M, 1C, and 1Bk in the drawing. The endless belt-shaped intermediate transfer body unit 7 includes an endless belt-shaped intermediate transfer body 70 that can be rotated by winding rollers 71, 72, 73, 74, primary transfer rollers 5Y, 5M, 5C, 5Bk, and cleaning means 6b. Consists of.

  Next, FIG. 4 shows a color image forming apparatus using the organic photoreceptor of the present invention (a copying machine having at least a charging means, an exposure means, a plurality of developing means, a transfer means, a cleaning means and an intermediate transfer body around the organic photoreceptor. 1 is a sectional view of the configuration of a laser beam printer). The belt-shaped intermediate transfer body 70 uses an elastic body having a medium resistance.

  Reference numeral 1 denotes a rotary drum type photoconductor that is repeatedly used as an image forming body, and is rotationally driven in a counterclockwise direction indicated by an arrow at a predetermined peripheral speed.

  During the rotation process, the photosensitive member 1 is uniformly charged to a predetermined polarity and potential by the charging unit 2 and then modulated in accordance with a time-series electric digital pixel signal of image information by an image exposure unit 3 (not shown). An electrostatic latent image corresponding to a yellow (Y) color component image of a target color image is formed by receiving image exposure with scanning exposure light or the like by a laser beam.

  Next, the electrostatic latent image is developed with yellow toner as the first color by yellow (Y) developing means (yellow color developing device) 4Y. At this time, the second to fourth developing means (magenta developer, cyan developer, black developer) 4M, 4C, and 4Bk are not activated and do not act on the photoreceptor 1. The yellow toner image of the first color is not affected by the second to fourth developing devices.

  The intermediate transfer member 70 is stretched by rollers 79a, 79b, 79c, 79d, and 79e, and is driven to rotate in the clockwise direction at the same peripheral speed as the photosensitive member 1.

  The first color yellow toner image formed and supported on the photosensitive member 1 is applied to the intermediate transfer member 70 from the primary transfer roller 5a in the process of passing through the nip portion between the photosensitive member 1 and the intermediate transfer member 70. The intermediate transfer (primary transfer) is sequentially performed on the outer peripheral surface of the intermediate transfer body 70 by the electric field formed by the primary transfer bias.

  The surface of the photoreceptor 1 after the transfer of the first color yellow toner image corresponding to the intermediate transfer body 70 is cleaned by the cleaning device 6a.

  Similarly, the second color magenta toner image, the third color cyan toner image, and the fourth color black (black) toner image are sequentially superimposed and transferred onto the intermediate transfer body 70 to correspond to the target color image. A superimposed color toner image is formed.

  The secondary transfer roller 5b is supported in parallel with the secondary transfer counter roller 79b so as to be separated from the lower surface of the intermediate transfer body 70.

  The primary transfer bias for sequentially superimposing and transferring the first to fourth color toner images from the photosensitive member 1 to the intermediate transfer member 70 has a polarity opposite to that of the toner and is applied from a bias power source. The applied voltage is, for example, in the range of +100 V to +2 kV.

  In the primary transfer process of the first to third color toner images from the photosensitive member 1 to the intermediate transfer member 70, the secondary transfer roller 5b and the intermediate transfer member cleaning means 6b can be separated from the intermediate transfer member 70. is there.

  When the superimposed color toner image transferred onto the belt-shaped intermediate transfer member 70 is transferred to the transfer material P, which is the second image carrier, the secondary transfer roller 5b is brought into contact with the belt of the intermediate transfer member 70. At the same time, the transfer material P is fed from the pair of paper registration rollers 23 through the transfer paper guide to the belt of the intermediate transfer body 70 to the contact nip with the secondary transfer roller 5b at a predetermined timing. A secondary transfer bias is applied to the secondary transfer roller 5b from a bias power source. By this secondary transfer bias, the superimposed color toner image is transferred (secondary transfer) from the intermediate transfer body 70 to the transfer material P as the second image carrier. The transfer material P that has received the transfer of the toner image is introduced into the fixing means 24 and heated and fixed.

  The organophotoreceptor of the present invention is generally applicable to electrophotographic apparatuses such as electrophotographic copying machines, laser printers, LED printers, and liquid crystal shutter printers, but also displays, recordings, light printing, plate making and facsimiles using electrophotographic technology. The present invention can be widely applied to such devices.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention concretely, this invention is not limited by these Examples. In addition, "part" in a sentence represents a mass part.

Example 1
A toner used in the present invention and a developer using the toner were prepared.

  Next, a toner was prepared as follows.

* Production of Toner 1-Bk 100 parts of styrene-acrylic resin having a mass ratio of styrene: butyl acrylate: butyl methacrylate = 80: 10: 10, 10 parts of carbon black, 5 parts of low molecular weight polypropylene (number average molecular weight = 3500) After melting and kneading, the mixture was finely pulverized using a mechanical pulverizer and carefully classified with an air classifier to obtain colored particles having a 50% volume particle diameter (Dv50) of 3.8 μm. To the colored particles, 1.2% by mass of hydrophobic silica (degree of hydrophobicity = 80 / number average primary particle size = 12 nm) was added to obtain a toner. This is referred to as “toner 1-Bk”.

* Production of Toner 2-Bk 100 parts of styrene-acrylic resin having a mass ratio of styrene: butyl acrylate: butyl methacrylate: acrylic acid = 75: 18: 5: 2; 10 parts of carbon black; low molecular weight polypropylene (number average molecular weight = 3500) After 5 parts are melted and kneaded, they are finely pulverized using a mechanical pulverizer, carefully classified by an air classifier and colored particles having a 50% volume particle diameter (Dv50) of 8.1 μm. Got. To the colored particles, 1.2% by mass of hydrophobic silica (degree of hydrophobicity = 80 / number average primary particle size = 12 nm) was added to obtain a toner. This is referred to as “toner 2-Bk”.

* Production of toner 3-Bk 100 parts of styrene-acrylic resin having a mass ratio of styrene: butyl acrylate: methacrylic acid = 70: 20: 10, 10 parts of carbon black, 4 parts of low molecular weight polypropylene (number average molecular weight = 3500) After being melted and kneaded, it was finely pulverized using a mechanical pulverizer and carefully classified by an air classifier to obtain colored particles having a 50% volume particle diameter (Dv50) of 4.8 μm. To the colored particles, 1.2% by mass of hydrophobic silica (hydrophobicity = 75 / number average primary particle size = 12 nm) was added to obtain a toner. This is referred to as “toner 3-Bk”.

* Preparation of Toner 4-Bk, Toner 4-Y, Toner 4-M, and Toner 4-C Sodium n-dodecyl sulfate = 0.90 kg and 10.0 L of pure water are added and dissolved with stirring. While stirring, 1.20 kg of Legal 330R (carbon black manufactured by Cabot) was gradually added to this liquid, and then continuously dispersed for 20 hours using a sand grinder (medium type disperser). After dispersion, the particle size of the dispersion was measured using an electrophoretic light scattering photometer ELS-800 manufactured by Otsuka Electronics Co., Ltd. As a result, the weight average particle size was 122 nm. Moreover, the solid content concentration of the dispersion measured by a mass method by standing drying was 16.6% by mass. This dispersion is referred to as “colorant dispersion 1”.

  0.055 kg of sodium dodecylbenzenesulfonate is mixed with 4.0 L of ion-exchanged water and dissolved by stirring at room temperature. This is referred to as an anionic surfactant solution A.

  0.014 kg of nonylphenyl alkyl ether is mixed with 4.0 L of ion-exchanged water and dissolved by stirring at room temperature. This is designated as a nonionic surfactant solution A.

  Potassium persulfate = 223.8 g is mixed with 12.0 L of ion-exchanged water and dissolved with stirring at room temperature. This is referred to as initiator solution A.

  In a 100 L reaction kettle equipped with a temperature sensor, a cooling pipe, and a nitrogen introducing device, 3.41 kg of a polypropylene emulsion having a number average molecular weight (Mn) of 3500, an anionic surfactant solution A, and a nonionic surfactant solution A were added. Start agitation. Then, 44.0 L of ion exchange water is added.

  When heating is started and the liquid temperature reaches 75 ° C., the initiator solution A is added in its entirety. Thereafter, while controlling the liquid temperature at 75 ° C. ± 1 ° C., 14.3 kg of styrene, 2.88 kg of n-butyl acrylate, 0.8 kg of methacrylic acid, and 548 g of t-dodecyl mercaptan are added.

  Furthermore, the liquid temperature was raised to 80 ° C. ± 1 ° C., and stirring was performed for 6 hours. Cool the liquid temperature below 40 ° C and stop stirring. It filtered with the pole filter and this was set as latex A1.

  The glass transition temperature of the resin particles in the latex A1 was 59 ° C., the softening point was 116 ° C., the molecular weight distribution was weight average molecular weight = 13.4 million, and the weight average particle size was 125 nm.

  Potassium persulfate = 200.7 g is mixed with 12.0 L of ion-exchanged water, and dissolved with stirring at room temperature. This is designated initiator solution B.

  The nonionic surfactant solution A is put into a 100 L reaction kettle equipped with a temperature sensor, a cooling pipe, a nitrogen introducing device, and a comb-shaped baffle, and stirring is started. Next, 44.0 L of ion exchange water is added.

  Heating is started, and when the liquid temperature reaches 70 ° C., the initiator solution B is added. At this time, a solution prepared by previously mixing 11.0 kg of styrene, 4.00 kg of n-butyl acrylate, 1.04 kg of methacrylic acid, and 9.02 g of t-dodecyl mercaptan is added.

  Thereafter, the liquid temperature was controlled to 72 ° C. ± 2 ° C., and the mixture was heated and stirred for 6 hours. Furthermore, the liquid temperature was raised to 80 ° C. ± 2 ° C., and the mixture was heated and stirred for 12 hours.

  Cool the liquid temperature below 40 ° C and stop stirring. It filtered with the pole filter and this filtrate was set to latex B1.

  The glass transition temperature of the resin particles in the latex B1 was 58 ° C., the softening point was 132 ° C., the molecular weight distribution was weight average molecular weight = 245,000, and the weight average particle size was 110 nm.

  Sodium chloride = 5.36 kg as salting-out agent and 20.0 L of ion-exchanged water are added and dissolved by stirring. This is designated as sodium chloride solution A.

  In a 100 L SUS reaction kettle (stirring blade is an anchor blade) equipped with a temperature sensor, a cooling pipe, a nitrogen introducing device, and a comb-shaped baffle, latex A1 = 20.0 kg and latex B1 = 5.2 kg prepared above and a coloring agent are dispersed. Liquid 1 = 0.4 kg and ion-exchanged water 20.0 kg are added and stirred. Then warm to 35 ° C. and add sodium chloride solution A. Then, after leaving for 5 minutes, the temperature rise is started, and the temperature is raised to 85 ° C. in 5 minutes (temperature rise rate = 10 ° C./min). The mixture is heated and stirred at a liquid temperature of 85 ° C. ± 2 ° C. for 6 hours to cause salting out / fusion. Then, it cools to 30 degrees C or less and stops stirring. The mixture is filtered through a sieve having an opening of 45 μm, and this filtrate is used as an association liquid. Subsequently, using a centrifuge, wet cake-like non-spherical particles were collected from the associated liquid by filtration. Thereafter, it was washed with ion exchange water.

  The wet cake-like colored particles that had been washed as described above were dried with hot air at 40 ° C. to obtain colored particles. Further, careful classification was performed with an air classifier to obtain colored particles having a 50% volume particle diameter (Dv50) of 4.2 μm. Further, 1.0% by mass of hydrophobic silica (hydrophobic degree = 70, number average primary particle diameter = 12 nm) was added to the colored particles to obtain “Toner 4-Bk”.

  In the production of toner 4-Bk, C.I. I. “Toner 4-Y” was obtained in the same manner except that 8 parts of Pigment Yellow 185 were used.

  In the production of toner 4-Bk, C.I. I. “Toner 4-M” was obtained in the same manner except that 10 parts of Pigment Red 122 was used.

  In the production of toner 4-Bk, C.I. I. “Toner 4-C” was obtained in the same manner except that 5 parts of Pigment Blue 15: 3 was used.

* Preparation of Toner 5-Bk, Toner 5-Y, Toner 5-M, and Toner 5-C Colored particles with different particle diameters were prepared by changing the fusing conditions of Toner 4-Bk. Further, careful classification was performed with an air classifier to obtain colored particles having a 50% volume particle size (Dv50) of 5.0 μm. To the colored particles, 1.0% by mass of hydrophobic silica (hydrophobic degree = 75, number average primary particle size = 12 nm) was added to obtain “Toner 5-Bk”.

  In the production of toner 5-Bk, C.I. I. “Toner 5-Y” was obtained in the same manner except that 8 parts of Pigment Yellow 185 were used.

  In the production of toner 5-Bk, C.I. I. “Toner 5-M” was obtained in the same manner except that 10 parts of Pigment Red 122 were used.

  In the production of toner 5-Bk, C.I. I. “Toner 5-C” was obtained in the same manner except that 5 parts of Pigment Blue 15: 3 was used.

* Production of Toner 6-Bk, Toner 6-Y, Toner 6-M, and Toner 6-C Colored particles having a 50% volume particle diameter (Dv50) of 9.5 μm were obtained by changing the classification conditions of Toner 5-Bk. . To the colored particles, 1.0% by mass of hydrophobic silica (hydrophobic degree = 75, number average primary particle size = 12 nm) was added to obtain “Toner 6-Bk”.

  In the production of the toner 6-Bk, C.I. I. “Toner 6-Y” was obtained in the same manner except that 8 parts of Pigment Yellow 185 were used.

  In the production of the toner 6-Bk, C.I. I. “Toner 6-M” was obtained in the same manner except that 10 parts of Pigment Red 122 were used.

  In the production of the toner 6-Bk, C.I. I. “Toner 6-C” was obtained in the same manner except that 5 parts of Pigment Blue 15: 3 was used.

* Production of Toner 7-Bk, Toner 7-Y, Toner 7-M and Toner 7-C 100 parts of polyester resin having an acid value of 45, 10 parts of carbon black, 5 parts of low molecular weight polypropylene (number average molecular weight = 3500) After melting and kneading, the mixture was finely pulverized using a mechanical pulverizer and carefully classified by an air classifier to obtain colored particles having a 50% volume particle diameter (Dv50) of 7.5 μm. To the colored particles, 1.2% by mass of hydrophobic silica (degree of hydrophobicity = 65 / number average primary particle size = 12 nm) was added to obtain a toner. This is referred to as “toner 7-Bk”.

  In the production of the toner 7-Bk, C.I. I. “Toner 7-Y” was obtained in the same manner except that 8 parts of Pigment Yellow 185 were used.

  In the production of the toner 7-Bk, C.I. I. “Toner 7-M” was obtained in the same manner except that 10 parts of Pigment Red 122 was used.

  In the production of the toner 7-Bk, C.I. I. “Toner 7-C” was obtained in the same manner except that 5 parts of Pigment Blue 15: 3 was used.

* Production of Toner 8-Bk, Toner 8-Y, Toner 8-M and Toner 8-C 100 parts of polyester resin having an acid value = 45, 10 parts of carbon black, 5 parts of low molecular weight polypropylene (number average molecular weight = 3500) After melting and kneading, the mixture was finely pulverized using a mechanical pulverizer and classified by an air classifier to obtain colored particles having a 50% volume particle diameter (Dv50) of 10.4 μm. To the colored particles, 1.2% by mass of hydrophobic silica (degree of hydrophobicity = 65 / number average primary particle size = 12 nm) was added to obtain a toner. This is referred to as “toner 8-Bk”.

  In the production of toner 8-Bk, C.I. I. “Toner 8-Y” was obtained in the same manner except that 8 parts of Pigment Yellow 185 were used.

  In the production of toner 8-Bk, C.I. I. “Toner 8-M” was obtained in the same manner except that 10 parts of Pigment Red 122 were used.

  In the production of toner 8-Bk, C.I. I. “Toner 8-C” was obtained in the same manner except that 5 parts of Pigment Blue 15: 3 was used.

  Table 1 shows the measurement results of the water content (mass%) of the toner in an environment of 30 ° C. and 80 RH%.

Preparation of Developer A ferrite carrier having a 50% volume particle diameter (Dv50) of 45 μm coated with a silicone resin is mixed with each of the above toners, that is, toner 1-Bk to toner 8-C (23 toners in total), Each developer having a toner concentration of 6% was prepared and evaluated. These 23 types of developer are designated as developer 1-Bk to developer 8-C, corresponding to the toner.

  The 50% volume particle size (Dv50) of the carrier is typically measured by a laser diffraction particle size distribution measuring device “HELOS” (manufactured by SYMPATEC) equipped with a wet disperser. Can do.

  Next, a photoreceptor used in the examples was prepared.

Preparation of photoreceptor 1 Intermediate layer 1
The following intermediate layer coating solution was applied by a dip coating method on a washed cylindrical aluminum substrate (processed to 10-point surface roughness Rz: 0.81 μm as defined in JISB-0601 by cutting) at 120 ° C. for 30 minutes. It dried and formed the intermediate | middle layer 1 with a dry film thickness of 3.0 micrometers.

  The following intermediate layer dispersion is diluted twice with the same mixed solvent, and is allowed to stand overnight and then filtered (filter; rigesh mesh filter made by Nippon Pole Co., Ltd., nominal filtration accuracy: 5 microns, pressure: 50 kPa). Produced.

(Preparation of intermediate layer dispersion)
Binder resin: (Exemplary polyamide N-1) 1 part (1.00 volume part)
Rutile titanium oxide A1 (number average primary particle size 35 nm; surface treatment using a copolymer of methylhydrogensiloxane and dimethylsiloxane (molar ratio 1: 1) in an amount of 5 mass% of the total mass of titanium oxide) 3 .5 parts (1.0 part by volume)
Ethanol / n-propyl alcohol / THF (= 45/20/30 mass ratio) 10 parts The above components were mixed and dispersed in a batch system for 10 hours using a sand mill disperser to prepare an intermediate layer dispersion. .

Charge generation layer The following components were mixed and dispersed using a sand mill disperser to prepare a charge generation layer coating solution. This coating solution was applied by a dip coating method to form a charge generation layer having a dry film thickness of 0.3 μm on the intermediate layer.

Charge-generating substance (G1): Y-type titanylphthalosin pigment having a maximum diffraction peak at 27.3 ° at the Bragg angle (2θ ± 0.2 °) of the characteristic X-ray diffraction spectrum of Cu-Kα
20 parts Silicone-modified polyvinyl butyral 10 parts 4-methoxy-4-methyl-2-pentanone 700 parts t-butyl acetate 300 parts Charge transport layer The following components were mixed and dissolved to prepare a charge transport layer coating solution. This coating solution was applied onto the charge generation layer by a dip coating method to form a charge transport layer having a dry film thickness of 25 μm.

Charge transport material (CTM-4) 70 parts Binder resin (Exemplary compound BPZ (Mv: 30000)) 100 parts Antioxidant (Exemplary compound 1-1) 8 parts Tetrahydrofuran / toluene (volume ratio 8/2) 750 parts Photoconductor Production of Nos. 2 to 6 Photoconductor 1 except that the N-type semiconductive particles of the intermediate layer, the binder resin, the dry film thickness, the charge generation material, the charge transport material of the charge transport layer, the film thickness, etc. were changed as shown in Table 2 Photoconductors 2 to 6 were produced in the same manner as described above. However, the volume ratio of the intermediate layer in Table 2 is the same as the volume of the binder resin and the volume of the binder resin, with the total volume of the binder resin and the volume of the N-type semiconductor particles in all the intermediate layers of the photoreceptors 1 to 6 being constant. An intermediate layer dispersion was prepared by changing the volume ratio (Vn / Vb) of the type semiconductive particles to form an intermediate layer.

At the same time as the production of the photoconductors 1 to 6, each intermediate layer coating solution was applied onto an aluminum-deposited polyethylene terephthalate support using the intermediate layer coating solution of each photoconductor. An intermediate layer having a dry film thickness of 10 μm was formed under the same conditions to prepare a volume resistance measurement sample, and the volume resistance of each intermediate layer was measured. As a result, the volume resistances of the intermediate layers of the photoreceptors 1 to 6 were all 1 × 10 ⁸ Ω · cm or more. The structural formula of the binder resin (BPZ) used for the photoreceptors 1 to 6 is shown below.

  In Table 2, G1, G2, and G3 represent the following charge generating substances.

G1: Y-type titanylphthalosin pigment having a maximum diffraction peak at 27.3 ° at the Bragg angle (2θ ± 0.2 °) of the characteristic X-ray diffraction spectrum of Cu-Kα G2 is a characteristic X-ray diffraction of Cu-Kα At least 7.5 °, 9.9 °, 12.5 °, 16.3 °, 18.6 °, 25.1 °, 28.1 ° at the Bragg angle of the spectrum (2θ ± 0.2 °) Hydroxygallium phthalocyanine pigment G3 having a characteristic diffraction peak at the position is at least 7.4 °, 16.6 °, 25.25 at the Bragg angle (2θ ± 0.2 °) of the characteristic X-ray diffraction spectrum of Cu-Kα. Chlorgallium phthalocyanine pigment having characteristic diffraction peaks at 5 ° and 28.3 ° A1 is rutile titanium oxide A2 is anatase titanium oxide * 1 is methylhydrogensiloxane and dimethylsilane Hexane copolymer (molar ratio 1: 1)
* 2 is a copolymer of methylhydrogensiloxane and dimethylsiloxane (molar ratio 9: 1)
* 3 is a copolymer of methylhydrogensiloxane and dimethylsiloxane (molar ratio 2: 8)
* 4 is a copolymer of methylhydrogensiloxane and diethylsiloxane (molar ratio 1: 1)
* 5: Copolymer of methylhydrogensiloxane and methylethylsiloxane (molar ratio 1: 1)
* 6 Methyl hydrogen polysiloxane In the table, the surface treatment refers to the substance used for the surface treatment applied to the surface of the particles.

  The heat of fusion and water absorption in the table were measured as follows.

Measurement conditions of heat of fusion Measuring machine: Measured using Shimadzu Corporation “Shimadzu heat flow rate differential scanning calorimeter DSC-50”.

  Measurement conditions: The measurement sample is set in the above-mentioned measuring machine, measurement is started from room temperature (24 ° C.), the temperature is raised to 200 ° C. at 5 ° C./min, and then cooled to room temperature at 5 ° C./min. This is repeated twice, and the heat of fusion is calculated from the endothermic peak area due to melting during the second temperature increase.

Measurement condition of water absorption rate The sample to be measured is sufficiently dried at 70 to 80 ° C. for 3 to 4 hours, and its mass is accurately weighed. Next, the sample is put into ion-exchanged water maintained at 20 ° C., and after a certain period of time, the sample surface is pulled up and wiped off with a clean cloth, and the mass is measured. The above operation was repeated until the increase in mass was saturated, and the value obtained by dividing the increased mass (increase) of the resulting sample by the initial mass was taken as the water absorption rate.

  In the table, the ratio of the unit structure having 7 or more carbon atoms refers to the ratio (mol%) of the repeating unit structure having 7 or more carbon atoms between amide bonds in the repeating unit structure.

Evaluation 1 (Evaluation by counter development method)
The obtained developer and the photoreceptor are combined as shown in Table 3 (combination Nos. 1 to 13), and a commercially available full-color composite machine 8050 (manufactured by Konica Minolta Business Technologies, Inc.) is remodeled (using an intermediate transfer member). A tandem-type full-color MFP 8050 (process speed 220 mm / sec) was mounted on a counter development system and modified to the following process conditions, and monochrome image evaluation using black toner was performed. Using an original image having a white background portion, a solid black portion solit image portion, and a character image portion, it was continuously copied and evaluated on A4 paper. Specifically, evaluation images were taken out at the start and every 5000 sheets, and a total of 300,000 sheets were printed and evaluated. Evaluation items and evaluation criteria are shown below.

Evaluation conditions The process conditions of the counter development method were evaluated using the following conditions.

Photoconductor linear velocity: 220 mm / sec
Magnetic brush bite depth (Bsd); 0.30mm
Development gap (Dsd); 0.28 mm
AC component of development bias (Vac); 1.0 KVp-p
Peripheral speed ratio of developing sleeve to photoreceptor (Vs / Vopc); 2.0
DC component of development bias (Vdc); -500V
Difference between the surface potential V0 of the photoreceptor and the DC component Vdc of the developing bias (| V0−Vdc |); 200V
Frequency: 5KHz
Duty: 50% rectangular wave For image evaluation, printing was performed at room temperature.
(1) Image evaluation: Density reduction at tip part A halftone image at 300,000 sheets was prepared and evaluated.

  (Double-circle): Generation | occurrence | production of density | concentration fall of a front-end | tip part is not seen, but a halftone image is reproduced clearly (very good).

  ○: The halftone image is clearly reproduced, but there is a drop in the tip density of less than 0.04 in reflection density (no problem in practical use).

  X: The half-tone image has a drop in tip density of 0.04 or more in reflection density (practically problematic).

At the start of fogging, a densitometer “RD-918” (manufactured by Macbeth) was used for the 300,000th sheet, and the fog density was measured at a relative density where the reflection density of A4 paper was 0.000.
A: Less than 0.010 (very good)
○: 0.010 or more and less than 0.020 (a level that causes no problem in practice)
×: 0.020 or more (problematic problems)
The results are shown in Table 3.

Image density At the start, a density meter “RD-918” (manufactured by Macbeth) was used for the 300,000th sheet, and the density was measured at a relative density of 0.0 on the printer paper.

A: 1.3 or more / good ○: 1.0 or more to less than 1.3 / practical problem level ×: less than 1.0 / practical problem

  As is apparent from Table 3, in the image evaluation produced by the counter development method, the toner contains toner particles having a particle size of 0.7 × (Dp50) or less, where the 50% number particle size of the toner particles is Dp50. Combination No. having an amount of 8% by number or less and a moisture content of 0.1 to 2.0% by mass (30 ° C., 80% RH environment). Nos. 1 to 10 show good characteristics in all evaluation items such as image density, fogging, and tip density reduction, whereas When a toner having a toner particle content 11 having a particle size of 0.7 × (Dp50) or less and greater than 8% by number is used, fogging and a decrease in tip density occur. Combination No. using a toner having a water content greater than 2.0 was also used. Reference numeral 12 indicates a decrease in image density and a decrease in tip density. Further, combination No. using a toner having a toner particle content greater than 8% by number and a water content greater than 2.0. No. 13 is a decrease in image density, occurrence of fogging, and a decrease in tip density.

Evaluation 2 (Evaluation using the parallel development method)
The evaluation performed in Evaluation 1 was evaluated by a parallel development system in which the traveling directions of the photosensitive member and the developing sleeve proceed in parallel.

Evaluation condition Photoconductor linear velocity: 220 mm / sec
Linear speed of developing sleeve: 44 mm / sec
As a result, the difference between the invention of the evaluation 1 and the comparative example did not appear clearly, and in all of the invention and the comparative example, no decrease in tip density or fog was observed, but compared with the counter development method. The image density was lowered, and an electrophotographic image with insufficient density was obtained.

Evaluation 3
Combination of photoconductor and toner as shown in Table 4 (combination Nos. 21-25), commercially available full-color composite machine 8050 (manufactured by Konica Minolta Business Technologies, Inc.), remodeling machine (tandem type full-color using an intermediate transfer member) The MFP 8050 (process speed 220 mm / sec) was mounted on a counter development system and modified to the following process conditions, and color images were evaluated.

  The evaluation was made by copying on A4 paper using an original image having a white background portion, a solid black portion, and a solid image portion and a character image portion of red, green, and blue. Specifically, a total of 300,000 sentence copy images were printed and evaluated at the start and every 5000 sheets. In addition to the evaluation performed in Evaluation 1, evaluation items were added by adding the following color reproducibility and worm-like unevenness.

  Evaluation was performed using the following conditions as the process conditions of the counter development system.

Photoconductor linear velocity: 220 mm / sec
Magnetic brush bite depth (Bsd); 0.50mm
Development gap (Dsd); 0.38 mm
AC component of development bias (Vac); 1.2 KVp-p
Peripheral speed ratio of developing sleeve to photoreceptor (Vs / Vopc); 2.3
DC component of development bias (Vdc); -550V
Difference between the surface potential V0 of the photoreceptor and the DC component Vdc of the developing bias (| V0−Vdc |); 200V
Frequency: 7KHz
Duty: 50% rectangular wave For image evaluation, printing was performed at room temperature.

Color reproducibility The color of the solid image portion of the secondary color (red, blue, green) in each of the Y, M, and C toners of the first image and the 100th image is measured by “Macbeth Color-Eye 7000”, and CMC The color difference between the first and 100th sheets of each solid image was calculated using the (2: 1) color difference formula.

A: Color difference is 3 or less (good)
×: Color difference is greater than 3 (practical problem and impractical)
Worm-like unevenness A halftone image of 10,000 sheets was observed with a magnifying glass (× 20), and the presence or absence of worm-like unevenness was observed and evaluated.

  A: Unevenness is not observed.

  A: There is no problem although there is some unevenness.

  X: There is unevenness. Visually wavy unevenness is practically problematic.

  The results are shown in Table 4.

  As is apparent from Table 4, the organic photoreceptor contains a charge generating material of a condensed polycyclic compound, and the toner has a particle size of 0.7 × (Dp50) where the 50% number particle size of the toner particles is Dp50. ) Combination No. 2 having the following toner particle content of 8% by number or less and a water content of 0.1 to 2.0% by mass (30 ° C., 80% RH environment). Nos. 21 and 22 have good evaluation of image density, fogging, tip density reduction and worm-like unevenness, and good color reproducibility. On the other hand, the combination No. When a toner having a toner particle content greater than 8% by number with a particle size of 23 × 0.7 (Dp50) or less is used, fogging and a decrease in tip density occur, and color reproducibility and worm-like unevenness also occur. It has deteriorated. Combination No. using toner having a water content higher than 2.0 In 24, the image density is lowered, the leading edge density is also lowered, and the color reproducibility is deteriorated. Further, combination No. using a toner having a toner particle content greater than 8% by number and a water content greater than 2.0. In No. 25, the image density is reduced, fogging and the tip density are also reduced, and color reproducibility and worm-like unevenness are deteriorated.

It is a figure which shows the cross section of the developing device of the counter direction developing method. 1 is a diagram illustrating an example of a schematic configuration of an electrophotographic apparatus having a process cartridge including an organic photoreceptor. 1 is a cross-sectional configuration diagram of a color image forming apparatus showing an embodiment of the present invention. 1 is a cross-sectional view of a color image forming apparatus using an organic photoreceptor of the present invention. .

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Organic photoreceptor C axis | shaft 2 Charging means 3 Exposure light 4 Developing means 5 Transfer means P Transfer material 24 Fixing means 6 Cleaning means Pex Pre-exposure means PC Process cartridge container AN Guide means 101 Organic photoreceptor 102 Developing apparatus 110 Developing container 118 Replenishment Port 120 Developing sleeve 121 Magnet 122 Developing blade 123 First conveying member 124 Second conveying member 128 Screw blade 130 Plate-like protrusion 140 Partition N1 Developing magnetic pole N2 Second developing magnetic pole S1 Pumping magnetic pole S2 Third conveying magnetic pole S3 First conveying magnetic pole P Developer drop position Q Pumping position

Claims (14)

An electrostatic latent image is formed on the organic photoconductor, a developing brush made of a developer containing toner is formed on a cylindrical developing sleeve, the developing brush is brought into contact with the organic photoconductor, and the electrostatic latent image is formed. In the image forming method for visualizing a toner image, the developer has a toner particle content of 0.7 × (Dp50) or less of 8 particles, where the 50% number particle size of the toner particles is Dp50. % And a toner having a water content of 0.1 to 2.0% by mass (under an environment of 30 ° C. and 80% RH). An image forming method characterized in that an electrostatic latent image is visualized as a toner image while being rotated. An electrostatic latent image is formed on the organic photoconductor, a developing brush made of a developer containing toner is formed on a cylindrical developing sleeve, the developing brush is brought into contact with the organic photoconductor, and the electrostatic latent image is formed. A plurality of image forming units each having a developing unit that visualizes a toner image and a transfer unit that transfers a toner image formed on an organic photoconductor to a transfer medium are provided, and the coloration is changed for each of the plurality of image forming units. In the image forming method of forming a color image by forming each color toner image on an organic photoreceptor using the prepared toner, and transferring the color toner image from the organic photoreceptor to a transfer medium, the developer contains toner particles. When the 50% number particle size is Dp50, the content of toner particles having a particle size of 0.7 × (Dp50) or less is 8 number% or less and the water content is 0.1 to 2.0% by mass (30 ° C. In an 80% RH environment) That contains toner with respect to the rotation direction of the organic photoreceptor, an image forming method characterized in that the electrostatic latent image into a toner image while rotating the developing sleeve in the counter direction. The toner has a ratio (Dv50 / Dp50) of 50% volume particle size (Dv50) to 50% number particle size (Dp50) of toner particles of 1.0 to 1.11. A toner having a ratio (Dv75 / Dp75) of 75% volume particle size (Dv75) to cumulative 75% number particle size (Dp75) from the larger number particle size of 1.0 to 1.10. The image forming method according to claim 1. The image forming method according to claim 1, wherein the toner particles have a 50% volume particle diameter (Dv50) of 2 to 9 μm. The organic photoreceptor has a photosensitive layer on an electrically conductive support through an intermediate layer containing N-type semiconductor particles having a number average primary particle size of 3 to 200 nm in a binder resin. The image forming method of any one of -4. The image forming method according to claim 5, wherein the N-type semiconductor particles are titanium oxide or zinc oxide. The image forming method according to claim 6, wherein the N-type semiconductor particles are titanium oxide. The image forming method according to claim 7, wherein the titanium oxide is a rutile titanium oxide pigment or an anatase titanium oxide pigment. The image forming method according to claim 1, wherein a development gap (Dsd) between the organic photoreceptor and the developing sleeve is 0.2 to 0.6 mm. The image according to any one of claims 1 to 9, wherein a biting depth (Bsd) of the magnetic brush in a developing region between the organic photoreceptor and the developing sleeve is 0.0 to 0.8 mm. Forming method. The image forming method according to claim 1, wherein a peripheral speed ratio (Vs / Vopc) between the developing sleeve and the organic photoreceptor is 1.2 to 3.0. The difference | V0−Vdc | between the surface potential V0 of the organic photoreceptor and the DC component Vdc of the developing bias applied to the developing sleeve is 100 to 300V, the DC component Vdc of the developing bias is −300V to −650V, 12. The image forming method according to claim 9, wherein the AC component Vac is 0.5 to 1.5 kV, a frequency of 3 to 9 kHz, a duty of 45 to 70%, and a rectangular wave. An electrostatic latent image is formed on the organic photoconductor, a developing brush made of a developer containing toner is formed on a cylindrical developing sleeve, the developing brush is brought into contact with the organic photoconductor, and the electrostatic latent image is formed. In the image forming apparatus that visualizes a toner image, the developer has a toner particle content of 0.7 × (Dp50) or less of 8 particles, where the 50% number particle size of the toner particles is Dp50. % And a toner having a water content of 0.1 to 2.0% by mass (under an environment of 30 ° C. and 80% RH). An image forming apparatus characterized in that an electrostatic latent image is visualized as a toner image while being rotated. An electrostatic latent image is formed on the organic photoconductor, a developing brush made of a developer containing toner is formed on a cylindrical developing sleeve, the developing brush is brought into contact with the organic photoconductor, and the electrostatic latent image is formed. A plurality of image forming units each having a developing unit that visualizes a toner image and a transfer unit that transfers a toner image formed on an organic photoconductor to a transfer medium are provided, and the coloration is changed for each of the plurality of image forming units. In the image forming apparatus for forming a color image by forming each color toner image on the organic photoreceptor using the prepared toner, and transferring the color toner image from the organic photoreceptor to a transfer medium, the developer contains toner particles. When the 50% number particle size is Dp50, the content of toner particles having a particle size of 0.7 × (Dp50) or less is 8 number% or less and the water content is 0.1 to 2.0% by mass (30 ° C. In an 80% RH environment) That contains toner with respect to the rotation direction of the organic photoreceptor, an image forming apparatus characterized by the electrostatic latent image into a toner image while rotating the developing sleeve in the counter direction.

Images